CVE-2021-28957: XSS
First published: Sun Mar 21 2021(Updated: )
A flaw was found in python-lxml. The HTML5 formaction attribute is not input sanitized like the HTML action attribute is which can lead to a Cross-Site Scripting attack (XSS) when an application uses python-lxml to sanitize user inputs. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
Credit: cve@mitre.org cve@mitre.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| pip/lxml | <4.6.3 | 4.6.3 |
| redhat/python-lxml | <0:4.2.3-3.el8 | 0:4.2.3-3.el8 |
| redhat/rh-python38-babel | <0:2.7.0-12.el7 | 0:2.7.0-12.el7 |
| redhat/rh-python38-python | <0:3.8.11-2.el7 | 0:3.8.11-2.el7 |
| redhat/rh-python38-python-cryptography | <0:2.8-5.el7 | 0:2.8-5.el7 |
| redhat/rh-python38-python-jinja2 | <0:2.10.3-6.el7 | 0:2.10.3-6.el7 |
| redhat/rh-python38-python-lxml | <0:4.4.1-7.el7 | 0:4.4.1-7.el7 |
| redhat/rh-python38-python-pip | <0:19.3.1-2.el7 | 0:19.3.1-2.el7 |
| redhat/rh-python38-python-urllib3 | <0:1.25.7-7.el7 | 0:1.25.7-7.el7 |
| debian/lxml | 4.3.2-1+deb10u4 4.6.3+dfsg-0.1+deb11u1 4.9.2-1 4.9.3-1 | |
| debian/lxml | <=4.3.2-1+deb10u2<=4.3.2-1<=4.6.2-1 | 4.6.3-1 4.3.2-1+deb10u3 |
| Lxml Lxml | <4.6.3 | |
| Debian Debian Linux | =9.0 | |
| Debian Debian Linux | =10.0 | |
| Fedoraproject Fedora | =33 | |
| Fedoraproject Fedora | =34 | |
| Netapp Snapcenter | ||
| Oracle ZFS Storage Appliance Kit | =8.8 | |
| redhat/python-lxml | <4.6.3 | 4.6.3 |
| <4.6.3 | ||
| =9.0 | ||
| =10.0 | ||
| =33 | ||
| =34 | ||
| =8.8 |
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Reference Links
- https://nvd.nist.gov/vuln/detail/CVE-2021-28957
- https://github.com/lxml/lxml/pull/316
- https://github.com/lxml/lxml/pull/316/commits/10ec1b4e9f93713513a3264ed6158af22492f270
- https://github.com/lxml/lxml/commit/2d01a1ba8984e0483ce6619b972832377f208a0d
- https://bugs.launchpad.net/lxml/+bug/1888153
- https://pypi.org/project/lxml
- https://lists.debian.org/debian-lts-announce/2021/03/msg00031.html
- https://github.com/lxml/lxml/commit/a5f9cb52079dc57477c460dbe6ba0f775e14a999
- https://www.debian.org/security/2021/dsa-4880
- https://security.netapp.com/advisory/ntap-20210521-0004/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ/
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://security.gentoo.org/glsa/202208-06
- https://github.com/advisories/GHSA-jq4v-f5q6-mjqq (Advisory)
- https://www.cve.org/CVERecord?id=CVE-2021-28957 https://nvd.nist.gov/vuln/detail/CVE-2021-28957
- https://bugzilla.redhat.com/show_bug.cgi?id=1941534
- https://access.redhat.com/errata/RHSA-2021:4151
- https://access.redhat.com/errata/RHSA-2021:4158
- https://access.redhat.com/errata/RHSA-2021:4160
- https://access.redhat.com/errata/RHSA-2021:4162
- https://access.redhat.com/errata/RHSA-2021:3254
- https://access.redhat.com/security/cve/cve-2021-28957
- https://security-tracker.debian.org/tracker/CVE-2021-28957
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-28957
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=985643
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1941535
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1941690
- 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://github.com/pypa/advisory-database/tree/main/vulns/lxml/PYSEC-2021-19.yaml
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3C2R44VDUY7FJVMAVRZ2WY7XYL4SVN45
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XXN3QPWCTQVOGW4BMWV3AUUZZ4NRZNSQ
- https://security.netapp.com/advisory/ntap-20210521-0004
Parent vulnerabilities
(Appears in the following advisories)
Frequently Asked Questions
What is CVE-2021-28957?
CVE-2021-28957 is an XSS vulnerability in the python `lxml` clean module versions before 4.6.3.
How does CVE-2021-28957 work?
CVE-2021-28957 allows a remote attacker to bypass the sanitizer by exploiting the `formaction` attribute in the HTML5 form.
Which software versions are affected by CVE-2021-28957?
The python `lxml` clean module versions before 4.6.3 are affected by CVE-2021-28957.
What is the severity of CVE-2021-28957?
CVE-2021-28957 has a severity rating of 6.1 (high).
How can CVE-2021-28957 be fixed?
To fix CVE-2021-28957, upgrade to python `lxml` clean module version 4.6.3 or later.
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