As we have just discussed in the C++ room, the current tag synonym system has one "security flaw": It is possible for a minority (5 users with a score of 5 in some obscure tag and 2.5k rep) to "hijack" a popular tag with thousands of questions. Doing so would certainly cause utter confusion, but my take on it was that, if they succeed, they have thousands of high-rep users in their tag when they only need a few downvotes to reverse that prank.

However, this answer by Nick Craver seems to imply that, once tag A has been made a synonym of B, all questions with the tag B will actually be changed to to have B instead, rather than just displaying tag A as B. If I understand that correctly, then this seems to be an invitation to wreak havoc on such a large scale that I have actually considered whether I should post that here.

Please tell me I'm wrong.


You're wrong in that old questions are not automatically retagged, but moderators can do that easily as they see fit. For examples, look through existing active synonyms for any with numbers next to the synonym tag; those have not yet been merged together.

When a synonym reaches a score of +4:

  • any new uses of the synonym tag are silently renamed to the master tag
  • only a moderator can remove the synonym link

I believe "new uses" includes new edits to old questions even if they don't touch tags.

  • On top of this, also recall that you cannot propose a synonym from a high quantity of tags to a lower quantity of tags, so as to prevent this from destroying high volume tags.
    – Grace Note StaffMod
    May 16 '11 at 15:11
  • @GraceNote: Apparently that restriction has been lifted, as [c++0x] (1,082 questions) was able to be proposed as a synonym of [c++11] (30 questions).
    – Fred Nurk
    May 16 '11 at 15:14
  • 3
    That's... very odd. Last I checked, all of the team was strictly opposed to allowing normal users to propose synonyms in that direction, so it's a bit surprising to see something like that retracted. Moreover, if I try to repeat this here on Meta, I get a warning that I cannot propose a synonym if the target has at least 1.25x the count. It's exceptionally weird that that one got through, then...
    – Grace Note StaffMod
    May 16 '11 at 15:16
  • Initially I thought I'd accept this answer, but then thought again. If, for example, 5 users from the C++ tag hijack the C# tag, then that will wreak havoc considerably in just the ten or twenty minutes it takes for a mod to notice and step in, just by retagging all new C# questions to C++ questions.
    – sbi
    May 16 '11 at 15:34
  • @sbi: Clarified.
    – Fred Nurk
    May 16 '11 at 15:36
  • 1
    @FredN: This still would leave the loophole I just mentioned, if it weren't for the mechanism Grace mentioned that should disallow obscure tags to hijack considerably more popular ones.
    – sbi
    May 16 '11 at 15:41
  • @Grace: Has this riddle been solved among the mods? How did Xeo do that if he shouldn't have been allowed to?
    – sbi
    May 16 '11 at 15:41
  • @sbi I'll let you know if I find anything out, but currently I've got nothing.
    – Grace Note StaffMod
    May 16 '11 at 15:42
  • @sbi: I originally read your question as havoc being caused by mass, multi-ten-thousands automatic renames caused by 5 pranksters (or 1 with 5 socks), but I do see that other havoc loophole for busy tags.
    – Fred Nurk
    May 16 '11 at 15:46
  • @Fred: In fact, that was my biggest concern, but now that this has been cleared up, there are those other loopholes to look at.
    – sbi
    May 16 '11 at 15:49
  • @sbi Can't say I got a response. Has it turned up again since? I'll see what I can do to push for further investigation to make sure this cannot happen, but if there's any other evidence we have to show for it, it'll make figuring out what allowed it, and consequently how to stop it, much easier.
    – Grace Note StaffMod
    May 24 '11 at 18:51
  • @Grace: I've never been involved in tag synonyms and haven't been since. Sorry, no further evidence from me. :(
    – sbi
    May 24 '11 at 18:54

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