Description
If the anti spam-captcha functionality in PluXml versions 5.8.22 and earlier is enabled, a captcha challenge is generated with a format that can be automatically recognized for articles, such that an automated script is able to solve this anti-spam mechanism trivially and publish spam comments. The details of captcha challenge are exposed within document body of articles with comments & anti spam-captcha functionalities enabled, including "capcha-letter", "capcha-word" and "capcha-token" which can be used to construct a valid post request to publish a comment. As such, attackers can flood articles with automated spam comments, especially if there are no other web defenses available.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | pluxml | No fix yet | — |
| Ubuntu 20.04 LTS | pluxml | No fix yet | — |
| Ubuntu 18.04 LTS | pluxml | No fix yet | — |
| Ubuntu 16.04 LTS | pluxml | No fix yet | — |