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CVE-2021-28957
Detail
Modified
This vulnerability has been modified since it was last analyzed by the NVD. It is awaiting reanalysis which may result in further changes to the information provided.
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.
NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.
Note: NVD Analysts have published a CVSS score for this CVE based on publicly available information at the time of analysis. The CNA has not provided a score within the CVE List.
NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.
Note: NVD Analysts have published a CVSS score for this CVE based on publicly available information at the time of analysis. The CNA has not provided a score within the CVE List.
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OR
*cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:*
Added
CPE Configuration
OR
*cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
*cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
Changed
Reference Type
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/ No Types Assigned
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/ Mailing List, Third Party Advisory
Changed
Reference Type
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/ No Types Assigned
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/ Mailing List, Third Party Advisory
Changed
Reference Type
https://security.netapp.com/advisory/ntap-20210521-0004/ No Types Assigned
https://security.netapp.com/advisory/ntap-20210521-0004/ Third Party Advisory
Changed
Reference Type
https://www.oracle.com/security-alerts/cpuoct2021.html No Types Assigned
https://www.oracle.com/security-alerts/cpuoct2021.html Patch, Third Party Advisory
lxml 4.6.2 allows XSS. It places the HTML action attribute into defs.link_attrs (in html/defs.py) for later use in input sanitization, but does not do the same for the HTML5 formaction attribute.
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.
Victim must voluntarily interact with attack mechanism
Added
CVSS V3.1
NIST AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Added
CWE
NIST CWE-79
Changed
Reference Type
https://bugs.launchpad.net/lxml/+bug/1888153 No Types Assigned
https://bugs.launchpad.net/lxml/+bug/1888153 Exploit, Issue Tracking, Third Party Advisory
Changed
Reference Type
https://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270 No Types Assigned
https://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270 Patch, Third Party Advisory
CVE Modified by MITRE3/21/2021 5:15:12 PM
Action
Type
Old Value
New Value
Changed
Description
lxml 4.6.2 places the HTML action attribute into defs.link_attrs (in html/defs.py) for later use in input sanitization, but does not do the same for the HTML5 formaction attribute.
lxml 4.6.2 allows XSS. It places the HTML action attribute into defs.link_attrs (in html/defs.py) for later use in input sanitization, but does not do the same for the HTML5 formaction attribute.
Quick Info
CVE Dictionary Entry: CVE-2021-28957 NVD
Published Date: 03/21/2021 NVD
Last Modified: 11/06/2023
Source: MITRE
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