Vulnerability Details : CVE-2021-28957
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.
Vulnerability category: Cross site scripting (XSS)
Exploit prediction scoring system (EPSS) score for CVE-2021-28957
Probability of exploitation activity in the next 30 days: 0.23%
Percentile, the proportion of vulnerabilities that are scored at or less: ~ 61 % EPSS Score History EPSS FAQ
CVSS scores for CVE-2021-28957
Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source |
---|---|---|---|---|---|
4.3
|
MEDIUM | AV:N/AC:M/Au:N/C:N/I:P/A:N |
8.6
|
2.9
|
NIST |
6.1
|
MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
2.8
|
2.7
|
NIST |
CWE ids for CVE-2021-28957
-
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.Assigned by: nvd@nist.gov (Primary)
References for CVE-2021-28957
-
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/
[SECURITY] Fedora 33 Update: python-lxml-4.5.1-4.fc33 - package-announce - Fedora Mailing-ListsMailing List;Third Party Advisory
-
https://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270
Add formaction attribute to defs.link_attrs by ColdHeat · Pull Request #316 · lxml/lxml · GitHubPatch;Third Party Advisory
-
https://security.netapp.com/advisory/ntap-20210521-0004/
CVE-2021-28957 lxml Vulnerability in NetApp Products | NetApp Product SecurityThird Party Advisory
-
https://bugs.launchpad.net/lxml/+bug/1888153
Error: Page not foundExploit;Issue Tracking;Third Party Advisory
-
https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999
Prepare release of lxml 4.6.3. · lxml/lxml@a5f9cb5 · GitHubPatch;Third Party Advisory
-
https://lists.debian.org/debian-lts-announce/2021/03/msg00031.html
[SECURITY] [DLA 2606-1] lxml security updateMailing List;Third Party Advisory
-
https://www.oracle.com/security-alerts/cpuoct2021.html
Oracle Critical Patch Update Advisory - October 2021Patch;Third Party Advisory
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https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/
[SECURITY] Fedora 34 Update: python-lxml-4.6.3-1.fc34 - package-announce - Fedora Mailing-ListsMailing List;Third Party Advisory
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https://security.gentoo.org/glsa/202208-06
lxml: Multiple Vulnerabilities (GLSA 202208-06) — Gentoo securityThird Party Advisory
-
https://www.debian.org/security/2021/dsa-4880
Debian -- Security Information -- DSA-4880-1 lxmlThird Party Advisory
Products affected by CVE-2021-28957
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
- cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
- cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:*
- cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
- cpe:2.3:a:netapp:snapcenter:-:*:*:*:*:*:*:*
- cpe:2.3:a:lxml:lxml:*:*:*:*:*:*:*:*