6.1

CVE-2021-28957: debian debian_linux

Modified
AliasesALPINE-CVE-2021-28957MGASA-2021-0246SUSE-SU-2022:3934-1
Published 21-03-2021Last modified 17-12-2025

Vulnerability summary

CVE-2021-28957 is a medium (CVSS 6.1) vulnerability in debian debian_linux. EPSS estimates a 4.04% chance of exploitation in the next 30 days, higher than 90.6% of scored vulnerabilities. 1 public exploit is recorded.

Priority
Routine

Not severe (CVSS 6.1, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
6.1/10
010
Medium · v3.1 (CVE.org)
EPSS score
4.04%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits1reference

Advisory lineage

Upstream 0 · Downstream 9 · Related 5
OPENSUSE-SU-2022:0803-1RHSA-2021:3254RHSA-2021:4151RHSA-2021:4160RHSA-2021:4162SUSE-SU-2022:0803-1

Timeline

  1. 21-03-2021
    PublishedVulnerability first disclosed.
  2. 17-12-2025
    Last modifiedVulnerability information updated.

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.

CVSS metrics

9 scores · 7 sources · 3 versions

EPSS trend

Probability

4.04%

Chance of exploitation in the next 30 days

Percentile

91%

Versus all other CVEs

30-day change

No change 0.00 pp

From 4.04% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

1 found
  • referenceUnverified

    Exploit Reference (bugs.launchpad.net)

    Maturity: unknown

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, user interaction (CVSS vector). Other conditions: not stated in public data.

Redhat4 products
  • python-lxml< 0:4.2.3-3.el8
  • python-lxml-debugsource< 0:4.2.3-3.el8
  • python3-lxml< 0:4.2.3-3.el8
  • python3-lxml-debuginfo< 0:4.2.3-3.el8
Suse3 products
  • python3-lxml&distro=SUSE Linux Enterprise Module for Public Cloud 12< 3.3.5-3.15.1
  • python3-lxml&distro=SUSE Linux Enterprise Server 12 SP5< 3.6.1-3.6.1
  • python3-lxml&distro=SUSE Linux Enterprise Server for SAP Applications 12 SP5< 3.6.1-3.6.1
Debian2 products
  • lxml< 4.3.2-1+deb10u3 | < 3.7.1-1+deb9u4 | < 4.6.3-1
  • debian_linuxEOL9.0 | 10.0
Mageia2 products
  • python-lxml< 4.3.0-1.3.mga7
  • python-lxml< 4.6.3-1.mga8
Alpine1 product
  • py3-lxml< 4.6.3-r0
Fedoraproject1 product
Lxml1 product
Netapp1 product
Opensuse1 product
  • translate-toolkit&distro=openSUSE Tumbleweed< 3.14.5-1.1 | < 3.3.6-1.3
Oracle1 product
PyPI1 product
  • lxml< a5f9cb52079dc57477c460dbe6ba0f775e14a999 | < 4.6.3
Ubuntu1 product
  • lxml< 3.5.0-1ubuntu0.4 | < 4.2.1-1ubuntu0.4 | < 4.5.0-1ubuntu0.3 | < 3.3.3-1ubuntu0.2+esm3

12 vendors · 19 products

References

40 links
Show all 40 references