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CVE-2021-28957

Published: Mar 21, 2021

Modified: Dec 17, 2025

PUBLISHED

Description

An XSS vulnerability was discovered in python-lxml's clean module versions before 4.6.3. When disabling the safe_attrs_only and forms arguments, the Cleaner class does not remove the formaction attribute allowing for JS to bypass the sanitizer. A remote attacker could exploit this flaw to run arbitrary JS code on users who interact with incorrectly sanitized HTML. This issue is patched in lxml 4.6.3.

Vendor	Product	Versions
n/a	n/a	affected `n/a`

References

https://bugs.launchpad.net/lxml/+bug/1888153

x_refsource_MISC

https://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270

x_refsource_MISC

[debian-lts-announce] 20210324 [SECURITY] [DLA 2606-1] lxml security update

mailing-list

x_refsource_MLIST

vendor-advisory

x_refsource_DEBIAN

FEDORA-2021-28723f9670

vendor-advisory

x_refsource_FEDORA

FEDORA-2021-4cdb0f68c7

vendor-advisory

x_refsource_FEDORA

https://www.oracle.com/security-alerts/cpuoct2021.html

x_refsource_MISC

https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999

x_refsource_MISC

https://security.netapp.com/advisory/ntap-20210521-0004/

x_refsource_CONFIRM

vendor-advisory

x_refsource_GENTOO

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