Ecosyste.ms: Advisories

Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLXE2NW0tcHYzZi13cjVy

XSS in Bleach when noscript and raw tag whitelisted

Impact

A mutation XSS affects users calling bleach.clean with noscript and a raw tag (see below) in the allowed/whitelisted tags option.

Patches

v3.1.1

Workarounds

• modify bleach.clean calls to not whitelist noscript and one or more of the following raw tags:

title
textarea
script
style
noembed
noframes
iframe
xmp

• A strong Content-Security-Policy without unsafe-inline and unsafe-eval script-srcs) will also help mitigate the risk.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1615315
• https://cure53.de/fp170.pdf
• https://nvd.nist.gov/vuln/detail/CVE-2020-6802
• 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 [email protected]

Permalink: https://github.com/advisories/GHSA-q65m-pv3f-wr5r
JSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLXE2NW0tcHYzZi13cjVy
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Moderate
Classification: General
Published: about 4 years ago
Updated: over 1 year ago

CVSS Score: 6.1
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Identifiers: GHSA-q65m-pv3f-wr5r, CVE-2020-6802
References:

• https://github.com/mozilla/bleach/security/advisories/GHSA-q65m-pv3f-wr5r
• https://github.com/mozilla/bleach/commit/f77e0f6392177a06e46a49abd61a4d9f035e57fd
• https://bugzilla.mozilla.org/show_bug.cgi?id=1615315
• https://cure53.de/fp170.pdf
• https://nvd.nist.gov/vuln/detail/CVE-2020-6802
• https://lists.fedoraproject.org/archives/list/[email protected]/message/72R4VFFHDRSQMNT7IZU3X2755ZP4HGNI/
• https://lists.fedoraproject.org/archives/list/[email protected]/message/OCNLM2MGQTOLCIVVYS2Z5S7KOQJR5JC4/
• https://lists.fedoraproject.org/archives/list/[email protected]/message/YTULPQB7HVPPYWEYVNHJGDTSPVIDHIZX/
• https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleach
• https://advisory.checkmarx.net/advisory/CX-2020-4276
• https://github.com/advisories/GHSA-q65m-pv3f-wr5r

Repository: https://github.com/mozilla/bleach
Blast Radius: 29.7

Affected Packages