CVE-2021-28957
Apache Lxml Formaction XSS
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.
INFO
Published Date :
March 21, 2021, 5:15 a.m.
Last Modified :
Nov. 7, 2023, 3:32 a.m.
Source :
[email protected]
Remotely Exploitable :
Yes !
Impact Score :
2.7
Exploitability Score :
2.8
Affected Products
The following products are affected by CVE-2021-28957
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2021-28957.
| URL | Resource |
|---|---|
| https://bugs.launchpad.net/lxml/+bug/1888153 | Exploit Issue Tracking Third Party Advisory |
| https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999 | Patch Third Party Advisory |
| https://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270 | Patch Third Party Advisory |
| https://lists.debian.org/debian-lts-announce/2021/03/msg00031.html | Mailing List Third Party Advisory |
| 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 | Third Party Advisory |
| https://security.netapp.com/advisory/ntap-20210521-0004/ | Third Party Advisory |
| https://www.debian.org/security/2021/dsa-4880 | Third Party Advisory |
| https://www.oracle.com/security-alerts/cpuoct2021.html | Patch Third Party Advisory |
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2021-28957 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2021-28957 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
May. 14, 2024
Action Type Old Value New Value -
CVE Modified by [email protected]
Nov. 07, 2023
Action Type Old Value New Value Added Reference MITRE https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/ [No types assigned] Added Reference MITRE https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/ [No types assigned] Removed Reference MITRE https://lists.fedoraproject.org/archives/list/[email protected]/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/ Removed Reference MITRE https://lists.fedoraproject.org/archives/list/[email protected]/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/ -
Modified Analysis by [email protected]
Dec. 09, 2022
Action Type Old Value New Value Changed Reference Type https://security.gentoo.org/glsa/202208-06 No Types Assigned https://security.gentoo.org/glsa/202208-06 Third Party Advisory -
CVE Modified by [email protected]
Aug. 10, 2022
Action Type Old Value New Value Added Reference https://security.gentoo.org/glsa/202208-06 [No Types Assigned] -
Modified Analysis by [email protected]
Dec. 06, 2021
Action Type Old Value New Value Changed Reference Type https://lists.fedoraproject.org/archives/list/[email protected]/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/ No Types Assigned https://lists.fedoraproject.org/archives/list/[email protected]/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/ Mailing List, Third Party Advisory Changed Reference Type https://lists.fedoraproject.org/archives/list/[email protected]/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/ No Types Assigned https://lists.fedoraproject.org/archives/list/[email protected]/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 Added CPE Configuration OR *cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* *cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Added CPE Configuration OR *cpe:2.3:a:netapp:snapcenter:-:*:*:*:*:*:*:* Added CPE Configuration OR *cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:* -
CVE Modified by [email protected]
Oct. 20, 2021
Action Type Old Value New Value Added Reference https://www.oracle.com/security-alerts/cpuoct2021.html [No Types Assigned] -
CVE Modified by [email protected]
Jun. 04, 2021
Action Type Old Value New Value Added Reference https://lists.fedoraproject.org/archives/list/[email protected]/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/ [No Types Assigned] -
CVE Modified by [email protected]
May. 28, 2021
Action Type Old Value New Value Added Reference https://lists.fedoraproject.org/archives/list/[email protected]/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/ [No Types Assigned] -
CVE Modified by [email protected]
May. 21, 2021
Action Type Old Value New Value Added Reference https://security.netapp.com/advisory/ntap-20210521-0004/ [No Types Assigned] -
Modified Analysis by [email protected]
Mar. 30, 2021
Action Type Old Value New Value Changed Reference Type https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999 No Types Assigned https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999 Patch, Third Party Advisory Changed Reference Type https://lists.debian.org/debian-lts-announce/2021/03/msg00031.html No Types Assigned https://lists.debian.org/debian-lts-announce/2021/03/msg00031.html Mailing List, Third Party Advisory Changed Reference Type https://www.debian.org/security/2021/dsa-4880 No Types Assigned https://www.debian.org/security/2021/dsa-4880 Third Party Advisory Changed CPE Configuration OR *cpe:2.3:a:lxml:lxml:4.6.2:*:*:*:*:*:*:* OR *cpe:2.3:a:lxml:lxml:*:*:*:*:*:*:*:* versions up to (excluding) 4.6.3 Added CPE Configuration OR *cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* *cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* -
CVE Modified by [email protected]
Mar. 30, 2021
Action Type Old Value New Value Added Reference https://www.debian.org/security/2021/dsa-4880 [No Types Assigned] -
CVE Modified by [email protected]
Mar. 29, 2021
Action Type Old Value New Value Changed Description 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. Added Reference https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999 [No Types Assigned] -
CVE Modified by [email protected]
Mar. 24, 2021
Action Type Old Value New Value Added Reference https://lists.debian.org/debian-lts-announce/2021/03/msg00031.html [No Types Assigned] -
Initial Analysis by [email protected]
Mar. 24, 2021
Action Type Old Value New Value Added CVSS V2 Metadata Victim must voluntarily interact with attack mechanism Added CVSS V2 NIST (AV:N/AC:M/Au:N/C:N/I:P/A:N) Added CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N 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 Added CWE NIST CWE-79 Added CPE Configuration OR *cpe:2.3:a:lxml:lxml:4.6.2:*:*:*:*:*:*:* -
CVE Modified by [email protected]
Mar. 21, 2021
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.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2021-28957 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2021-28957
weaknesses.
Exploit Prediction
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.
0.23 }} -0.02%
score
0.61286
percentile