Описание
Bleach vulnerable to mutation XSS via whitelisted math or svg and raw tag
Impact
A mutation XSS affects users calling bleach.clean with all of:
- the
svgormathin the allowed/whitelisted tags - an RCDATA tag (see below) in the allowed/whitelisted tags
- the keyword argument
strip=False
Patches
Users are encouraged to upgrade to bleach v3.1.2 or greater.
Workarounds
- modify
bleach.cleancalls to usestrip=True, or not whitelistmathorsvgtags and one or more of the following tags:
- A strong Content-Security-Policy without
unsafe-inlineandunsafe-evalscript-srcs) will also help mitigate the risk.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1621692
- https://cure53.de/fp170.pdf
- https://nvd.nist.gov/vuln/detail/CVE-2020-6816
- https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleach
Credits
- Reported by Yaniv Nizry from the CxSCA AppSec group at Checkmarx
For more information
If you have any questions or comments about this advisory:
- Open an issue at https://github.com/mozilla/bleach/issues
- Email us at security@mozilla.org
Ссылки
- https://github.com/mozilla/bleach/security/advisories/GHSA-m6xf-fq7q-8743
- https://nvd.nist.gov/vuln/detail/CVE-2020-6816
- https://advisory.checkmarx.net/advisory/CX-2020-4277
- https://github.com/mozilla/bleach/releases/tag/v3.1.2
- https://github.com/pypa/advisory-database/tree/main/vulns/bleach/PYSEC-2020-28.yaml
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/EDQU2SZLZMSSACCBUBJ6NOSRNNBDYFW5
- https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleach
Пакеты
bleach
< 3.1.2
3.1.2
Связанные уязвимости
In Mozilla Bleach before 3.12, a mutation XSS in bleach.clean when RCDATA and either svg or math tags are whitelisted and the keyword argument strip=False.
In Mozilla Bleach before 3.12, a mutation XSS in bleach.clean when RCDATA and either svg or math tags are whitelisted and the keyword argument strip=False.
In Mozilla Bleach before 3.12, a mutation XSS in bleach.clean when RCD ...
Уязвимость библиотеки для очистки HTML на основе белых списков python-bleach, позволяющая нарушителю оказать воздействие на целостность данных
