CVE-2021-28957
Estado: ModificadaMedia (6.1)—
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.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- Puntuación base: 6.1
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 4.04%
- Percentil entre todas las CVEs puntuadas: 90
- Fecha de la puntuación: 7/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (5)
CWE
- CWE-79
- CWE-79
Referencias
- https://bugs.launchpad.net/lxml/+bug/1888153
- https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999
- https://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270
- https://lists.debian.org/debian-lts-announce/2021/03/msg00031.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/
- https://security.gentoo.org/glsa/202208-06
- https://security.netapp.com/advisory/ntap-20210521-0004/
- https://www.debian.org/security/2021/dsa-4880
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://bugs.launchpad.net/lxml/+bug/1888153
- https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999
- https://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270
- https://lists.debian.org/debian-lts-announce/2021/03/msg00031.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/
- https://security.gentoo.org/glsa/202208-06
- https://security.netapp.com/advisory/ntap-20210521-0004/
- https://www.debian.org/security/2021/dsa-4880
- https://www.oracle.com/security-alerts/cpuoct2021.html
JSON original (NVD)
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