CVE-2016-9909 — Improper Neutralization of Input During Web Page Generation in html5lib

Description

The serializer in html5lib before 0.99999999 might allow remote attackers to conduct cross-site scripting (XSS) attacks by leveraging mishandling of the < (less than) character in attribute values.

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.

Debian

Security tracker ↗

Release	Package	Fixed in	Advisory
Debian 14	html5lib	0.999999999-1	—
Debian 13	html5lib	0.999999999-1	—
Debian 12	html5lib	0.999999999-1	—

Ubuntu

Security tracker ↗

Release	Package	Fixed in	Advisory
Ubuntu 16.04 LTS	html5lib	No fix yet	—

Affected packages

Ecosystem	Package	Affected	Fixed	Record
PyPI	html5lib	< 0.999999999	0.999999999	GHSA-v9v9-xffq-rwr4

References

https://github.com/html5lib/html5lib-python/issues/12
https://html5lib.readthedocs.io/en/latest/changes.html#b9
[oss-security] 20161206 CVE Request: html5lib: potential cross-site scripting vulnerablity: quote attributes that need escaping in legacy browsers mailing-list
[oss-security] 20161208 Re: CVE Request: html5lib: potential cross-site scripting vulnerablity: quote attributes that need escaping in legacy browsers mailing-list
95132 vdb-entry
https://github.com/html5lib/html5lib-python/commit/9b8d8eb5afbc066b7fac9390f5ec75e5e8a7cab7
https://github.com/html5lib/html5lib-python/issues/11