‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​It's possible to create empty content fields - particularly question titles and bodies - on sites

Question

‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​Prior to an edit, this question was posted with no content in it, both in the title and the question body.

Screenshot of the current post before it was edited. The Meta banner is visible as is the score and other elements of the page but the title space and post body are completely empty of text, showing only the post notice banner stating that the post was migrated from Meta Stack Overflow

The explanation to reproduce is provided in Temani Afif's answer.

Since this was discovered, similar text fields around the site have been found to have similar issues and they are outlined in the answers below.

Note from Catija:

While we appreciate all the effort y'all have gone to to test and find places this is possible, we'd like this question to be understandable so that seeing it doesn't cause confusion. Feel free to add additional information to this answer but please leave the question itself as-is. Also, while y'all are free to continue to seek out these issues, we hope that you would all refrain from actually abusing this feature.

• Temani Afif: We can even submit empty questions. This need to be fixed
• Larnu: This was incredibly hard to get to; nothing is clickable from the Tagged Questions page. Why would you do this?!
• Gert Arnold: Duplicate: Can we create invisible things?.
• Ollie: I still can't stop laughing... You know how BAD this looks in the followed posts menu??
• Adam Lear: @Ollie Honestly... not really worse than it looks in the questions list. I expected something more horrifying :)
• Journeyman Geek: Chat oneboxen of this post are also not clickable... which is fun cause I thew this into a chatroom to keep an eye on it...
• Sebastian Simon: Doesn’t Stack Exchange use a bug tracker internally with questions being automatically added as soon as they get the status-review tag? I’m wondering what this question looks like in the bug tracker.
• Glorfindel: Staff, while you're at it, please have a look at my similar request for usernames.
• fedorqui 'SO stop harming': Related: Zero-width non-joiner allows unclickable titles
• Temani Afif: @fedorqui'SOstopharming' another one: meta.stackexchange.com/q/10519/386331 ... seems like I ressurected a very very old bug after 10 years
• Henry WH Hack v3.1.0a: So this is like Winter Bash, but instead of hunting for hats we are hunting for places we can post empty stuff.
• Journeyman Geek: Not really no. Its meta being meta and testing things to destruction, like infinite monkeys with infinite bolts of silk recreating the works of Christo :D
• Glorfindel: Given the answers, I was tempted to add the fun tag... Apparently we're all still in Winter Bash mode :)
• Ollie: I'm laughing at the "Needs details or clarity" close vote here... how could you make the problem any clearer?
• 10 Rep: @ᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠ why, just why do you have to do this?

Answer 1

status-completed

As we can not see, I was able to submit an empty question.

To reproduce it:

1. Submit a question with a content
2. Right after the submission, edit the question to remove everything and include invisible zero-width spaces.

Edit the below snippet to be able to see the spaces (they will show as red dots if you are using Chrome)

‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​

---

The system didn't allow me to submit the question initially due to the quality check but there was no quality check after edits.

---

We can, by the way, submit empty answers without the need of an edit after (see this answer).

• Larnu: I can see this is going to be a real pain to stop people doing this, but also I suspect that it's going to be unlikely be abused. If anything, if someone does this with malicious intent they'll likely just going to get stern words from the mods. Though, I won't lie, the whole thing is really amusing. It would be even better if we'd all lumped in to post "blank" comments and answers. ;)
• Temani Afif: @Larnu and using blank usernames ;)
• Larnu: That is the stuff of nightmares.
• Gert Arnold: Don't focus too much on visibility. Although the content isn't visible, it's clearly visible that (on the main sites) this would be deliberate malpractice, making it not different than any other malpractice, which community moderation is perfectly capable of dealing with.
• Temani Afif: @GertArnold why waiting for moderation intervention when we can prevent this from happening? Few more tests on the content should do it.
• Sebastian Simon: "if you are using Chrome" — Works in Firefox, too, at least using Nightly 86.0a1.
• ben is uǝq backwards: It's not a real pain to stop people doing this @Larnu alter table Posts add constraint ChkPostBodyLength check (datalength(body) > 100); (repeat for all fields with user input text).
• Larnu: @benisuǝqbackwards a zero width unicode character has a value of 2 for datalength, so 50 of them, and done. But that would also force users to post comments that are 50 characters long. That is far from desired.
• ben is uǝq backwards: The length could be different for different fields @Larnu, but you're right about the spaces having a length. You'd have to replace them first before performing the length which would make longer strings (i.e. posts) a real pain at scale.
• Shog9: Stripping leading/trailing spaces (including zws, zwj, etc) was routinely done on submission for years, @ben. It led to some other obscure bugs, so I'm guessing someone fixed them by moving the check without considering the implications.
• user688097: LOL, this is so funny.
• user152859: @KylePollard can you please explain what exactly is completed? I prefer not to test in order to see.
• Sonic the Anonymous Hedgehog: Yeah, now that the bug is allegedly fixed, can the method previously used to exploit it be publicly disclosed?
• Kyle Pollard: @ShadowWizard This has been fixed since September 2022 and got updated in the tracking table but this answer didn't get updated. You shouldn't be able to make empty questions anymore.

Answer 2

Oh boy:

enter image description here

We can use it to raise empty custom flags (status-completed). Empty tag wikis, too (not completed).

• Ollie: Please don't, though.
• Temani Afif: The stackexchange team must be hating me .. I opened the pandora's box ...
• Ollie: @TemaniAfif The Stack Exchange community is loving you, if the upvotes are anything to tell by ;)
• VLAZ: @TemaniAfif and that box is apparently full of emptyness.
• Jack B Nimble: @TemaniAfif But the last thing left in the box, is hope.
• user152859: @KylePollard here as well, there are two different bugs reported: submitting empty custom flag, and empty tag wiki. Are both now fixed i.e. can't submit empty content anymore?
• Kyle Pollard: @ShadowWizard My bad, I didn't see that there were two reports in one. I've just fixed the empty custom flag. We didn't look at empty tag wikis yet.

Answer 3

status-completed

I can also use this method to screw up my "About Me" section, e.g., remove the text "Your about me is currently blank", and the "Apparently this user prefers to keep an air of mystery about them" that y'all see:

enter image description here

Go take a look in my profile.

• rgettman: Rep for Nothing
• Temani Afif: @rgettman badges for nothing
• Cody Gray: I'd say that this is by-design. Users should be able to have an empty "About Me" section, if they like.
• Ollie: @CodyGray They can, but empty profiles always show the "Apparently, this user preferred to shroud themselves in a veil of mystery" or the like.
• Cody Gray: Yeah, but what if I don't want that silliness? Seems reasonable to allow its removal. What I'm saying is, there shouldn't be a content requirement for profile pages like there needs to be for posts.
• Ollie: @CodyGray By all means go ahead and make an FR, but I'm just posting the bug according to the current settings.
• Cody Gray: What I'm saying is, I disagree that this is a bug.
• user152859: Answer outdated, showing old avatar and also they now simply don't show the About Me section at all when there's no content.

Answer 4

Thanks to @ppwater, the empty tag now has an empty excerpt and wiki. See the tag info page.

• Temani Afif: not as empty as it should be. I made it even more empty ;) [let's wait for peer approval]
• Sonic the Anonymous Hedgehog: This is nothing new. If you initially propose them as suggested edits and they get rejected, they'll be blank anyway.
• bobble: The tag no long exists, making the link to the tag info page dead.
• user152859: @bobble is correct, answer has no value now. :-(
• Glorfindel: It's function is to share the fun we all had with this bug report ...

Answer 5

status-completed

Empty bounty summary:

enter image description here

See Where I started the bounty. (Now awarded)

• Temani Afif: and an empty duplicate banner: meta.stackexchange.com/q/359301/386331

Answer 6

There's no clickable area to this post from the 10k tools' Delete Votes page (there's an answer here with a pending delete vote).

Unclickable delete vote entry

Even on posts I'm unable to vote to delete/undelete, I can still click the link to hop to that post from this entry.

Not super unique (I mean, we already know the title is unclickable) but I see other answers documenting places where this affects accessibility and figured I would add this to the list.

Answer 7

4

I don't think I need any further explanations. I can create an empty room name using the ‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​ symbol.

Answer 8

status-completed

Empty suggested edit summary. (I edited Ollie's answer) approved edit enter image description here

Edit view:

enter image description here

• Ollie: Suggested no longer, as I approved it.

Answer 9

Summary of locations where this issue occurs, posted as answers

Want to contribute? Great! But please read the notes at the bottom of this post first.

Summary	Status
Empty display name	status-completed
Empty question	status-completed
Empty "About me"	status-completed
Empty custom flag	status-completed
Empty chat message
Empty (suggested) edit summary	status-completed
Empty bounty summary	status-completed
Empty tag excerpt and wiki
Empty suggested edit rejection reason
Empty chat room name
Empty chat room tag
No clickable area when empty post is found via a tag search
Empty "other off-topic" close reason	status-completed
No clickable area in 10k tools' "Delete Votes" page
Empty password
Empty site proposal name on Area 51
Alternative method to publish such empty posts
Empty answer using a 1x1 transparent pixel
Inconsistent display of the empty character in SEDE queries
No clickable area in followed posts list
Empty "Achievements" dropdown dialog
Empty badges
No clickable area in chat onebox
Empty duplicate banner
Empty comment	status-completed
Empty user annotation

Notes

• Anybody is welcome to contribute to this post; it's a Community wiki after all.
• Sorting order: status-completed > status-deferred > status-declined > status-planned > status-review > status-bydesign > no status tag.
• Comments can be used to discuss the structure of this post, e.g. whether the sort order above makes sense or needs to be improved.

Credits

Essentially copied the format from here.

• JNat: I created this answer as a placeholder, and will be filling it up early next week (lot on my plate this week). In case folks wanna start contributing, though, have at it! ^_^
• The Amplitwist: Some issues have been mentioned only in the comments. These are what I could find: empty comments, no clickable area in followed posts list, broken chat oneboxes, and (apparently) empty duplicate banner.
• JNat: Prolly ok to add to the main post, @TheAmplitwist . Also, thanks for filling that table in ^_^
• The Amplitwist: Sure, I'll do that. Happy to help :)
• Luuklag: I would say that the empty duplicate banner is not a real issue here, since that's just because the post title is empty cc@TheAmplitwist
• The Amplitwist: @Luuklag Perhaps that reasoning is also applicable to the "no clickable area" issues, since they, too, only occur because of the empty post title/body. Sure, they can be removed from this list if it's clear that they don't need to be tracked.
• This_is_NOT_a_forum: Empty is not the same as invisible. For instance, invisible characters, even zero-width, can still (blindly) be selected by Shift + arrow key right (at least in edit views). And copied. If not zero-width it might take up space when rendered. Is this problem about using invisible characters?
• Kyle Pollard: As part of the Community Asks sprint, we spent some time fixing the validation in a common library function. It now has an extra check for invisible strings, just like usernames do. I marked the ones that we looked at as fixed, though its possible others have been fixed since it's shared validation logic.

Answer 10

Empty reject reason:

Empty custom close reason:

enter image description here

• Temani Afif: i.sstatic.net/kxnvS.png

Answer 11

It turns out I can have zero-width characters in my password, although I also need to add one letter and one number.

• mindstormsboi: Best password ever.
• OrangeDog: In this case I don't think it's a problem, as it won't be displayed anywhere. If you want to make your password difficult to type, that's up to you.
• Ollie: Why did you deface your username? Now it's impossible to find anything of yours! Also see meta.stackexchange.com/review/suggested-edits/76648, there's already a post that did that.

Answer 12

People are vandalising their questions into "no title, no body" questions. Here is an example (see revision 3).

This is the 2nd or 3rd time I am seeing this happen in the wild...

---

People testing it out in answers:

enter image description here

• Temani Afif: flag such behavior .. vandalism isn't something new. I'd prefer empty content rather than bad words
• user152859: Agree with @Temani - that's just one way to vandalize, they can also edit it into "plz delete" over 100 lines, seen it done countless times. High rep users can rollback, and if it goes on moderator can suspend the problematic user and/or lock the post.
• 10 Rep: If you see this then flag. It's no different from normal vandalism.
• Sabito: Another test : meta.stackexchange.com/a/361810/598066

Answer 13

I posted here earlier that the issue had been fixed, but it's reported that the issue still persisted. I just moved it back to status-review.

Update 7/15/2022: The previous fix was grouping consecutive zero width characters into a single one when we validate the post length, which fixed the issue on my machine If I used the steps listed here to reproduce it.

We looked at this issue again and decided to remove all zero width characters when validating length. This change only affects length validation, and it doesn't actually remove the characters.

• Temani Afif: not for me, I was able to submit an empty answer: meta.stackexchange.com/a/379735/386331
• user152859: If you will elaborate what exactly has been fixed, maybe we can point out what's still missing? (e.g. if you only fixed the bug allowing to submit empty questions, there's still a bug when posting empty answers.)
• Shiyao Li: We added a check to remove all zero width spaces and zero width non joiners when we validate question and answer body. I wasn't able to submit an empty answer just now. But I'll change this back to status review.
• user152859: Well probably the trick is using something else, @TemaniAfif can you please elaborate how exactly you were able to post empty answer yesterday? What characters were used?
• Temani Afif: @ShadowWizardSaysNoMoreWar check the most upvoted answer. I already detailed how to create empty question/answer
• user152859: @ShiyaoLi the bug report is about many places where users can submit empty content, you fixed only empty posts. I don't think it is status-completed, unless you prefer to have each as a separate bug report?
• JNat: I created this post to start keeping track of all the places where this issue is occurring, so we can better track it, @ShadowTheKidWizard — feel free to start filling it up ;)

Answer 14

‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​What interests me is that no matter where I put the magic dots, they don't render. Search engine, Notepad, Notepad++, IDLE, PyCharm, etc. None of them rendered the actual dots.

Also, it's not possible to put your profile name as these characters. This is what happens when you try:

Trying it out

That doesn't mean answers and questions should work the same way, though.

Lastly, this:

Bruh https://en.wiktionary.org/wiki/bruh#Noun_2

Why do you have to do this to me?

Also, I've tried this on Codidact.

• Ollie: Truly, it is diabolical. Also hilarious.
• Temani Afif: they render as zero-width space ;) In the HTML/CSS world, it's useful.
• Temani Afif: some related posts where I used such magic: stackoverflow.com/a/62322234/8620333 / stackoverflow.com/a/57896638/8620333 / stackoverflow.com/a/64608352/8620333)

Answer 15

As relaxed as chatroom tags already were, we can also have empty tag identifiers.

Example of an empty chatroom tag

The same can't be said about tags created through the [tag:...] format.

Answer 16

You can post empty chat messages with this trick:

enter image description here

• Temani Afif: yes was going to edit my answer to include it too ;)
• Ollie: @TemaniAfif too late ;)

Answer 17

There is also another method I found that will do all the things posted so far (credit to a vandal). The characters are in the below snippet:

ᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠᅠIt stops here. Copy/paste the chars <-- from "It".

They are Korean Unicode characters - a Hangul filler (U+3164).

• Mast: "I'm still trying to find out what they are." It appears to be Korean Unicode, a Hangul filler (U+3164).
• Sebastian Simon: Yes, there are several nonprintable Unicode characters, e.g. ⠀ (U+2800), the blank Braille character. I don’t think it’s necessary to add another answer for each one of them. It doesn’t even matter if Stack Exchange fixes the ZWSP bug for all nonprintables or just for U+200B, as ⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁⠁ would be an equally low-quality post and should not be accepted anyway.

Answer 18

status-completed

One can use Unicode combining characters to produce an almost empty display name.

enter image description here

Try it yourself:

const textarea = document.querySelector('textarea');
document.querySelector('button').addEventListener('click', function(e){
 textarea.focus();
 textarea.select();
 document.execCommand('copy');
 textarea.blur();
});

Select all and copy in the textarea below or 
press the Copy button to get an almost empty 
display name you can set. <br>
<textarea readonly>̣̣̣</textarea> <br>
<button>Copy</button>

• iBug says Reinstate Monica: It's Unicode combining characters, right?
• Unmitigated: @̣̣̣ Yes. I see you've tried it.
• Kyle Pollard: This has been fixed - display names cannot consist entirely of malformed combining characters or other similarly invisible characters. They must contain at least one visible character (in addition to the other rules that already existed).
• user152859: @KylePollard how can you tell 1) when combining characters are malformed?, 2) whether a character is visible or not?
• Kyle Pollard: For visibility, we checks each Rune of the string for it's UnicodeCategory. A display name must contain at least one rune having the category Letter, Number, Punctuation, or Symbol categories. (eg. ModifierLetter or OtherPunctuation)
• Kyle Pollard: A malformed combining character would be one that's not combined with another character. For example, you can add the combining character representing an acute accent◌́ (U+0301) with e (U+0065) to get é (U+0065 U+0301), like in Pokémon. Note that this is a different than the single character than é (U+00E9). If you were to put just the combining character ` ◌́ ` (U+0301) on it's own, it would be malformed because it's not combined. Some programs add ◌ (U+25CC) to represent that there should have been a character, but others just reject it outright.

Answer 19

status-completed

||||||

The | bars are for indicating the edges of the image.

Empty "other off-topic close reason" indeed.

Answer 20

It's still possible for ♦ moderators to add empty user annotations (which have a minimum length of 10 characters):

enter image description here

Answer 21

It works on the Area 51 Stack Exchange site:

Enter image description here ‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​

It doesn't work on example questions as far as I know.

• Henry WH Hack v3.1.0a: Yes I know Area51.SE uses old code.

Answer 22

I can make a SEDE query with this now: SELECT * FROM Posts WHERE Body='%‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​‎​%';

I am using Chrome, but it does not appear as a red dot in here

But in SEDE: not really bugged

But, if I visit its saved link:
bugg

Answer 23

Unlike on the main questions feed, there is no clickable area I can find for this question on a tag search: https://meta.stackexchange.com/questions/tagged/empty

Screenshot of question

• Luuklag: How about "Edited 2 mins ago by OrangeDog"...
• Temani Afif: it's only available on my profile or the active tab
• OrangeDog: @Luuklag there is no such text
• OrangeDog: @TemaniAfif it's also clickable in the "Linked" section from other questions
• Luuklag: @OrangeDog that's because you sort on Newest, and not on Active
• ppwater: You can access with <kbd>Tab</kbd> + <kbd>Enter</kbd>
• 10 Rep: @ppwater enjoying the limited markdown in comments? :D
• riQQ: @10Repsaysgetvaccinated that's not markdown :P