---
id: CVE-2025-6069
title: >-
The html.parser.HTMLParser class had worse-case quadratic complexity when
processing certain crafted malformed inputs potentially leading to amplified
denial-of-service.
summary: >-
The html.parser.HTMLParser class had worse-case quadratic complexity when
processing certain crafted malformed inputs potentially leading to amplified
denial-of-service.
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L'
cwe:
- CWE-1333
published: '2025-06-17'
updated: '2026-07-30'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-6069'
references:
- url: >-
https://github.com/python/cpython/commit/4455cbabf991e202185a25a631af206f60bbc949
label: cna@python.org
- url: >-
https://github.com/python/cpython/commit/6eb6c5dbfb528bd07d77b60fd71fd05d81d45c41
label: cna@python.org
- url: >-
https://github.com/python/cpython/commit/8d1b3dfa09135affbbf27fb8babcf3c11415df49
label: cna@python.org
- url: >-
https://github.com/python/cpython/commit/ab0893fd5c579d9cea30841680e6d35fc478afb5
label: cna@python.org
- url: >-
https://github.com/python/cpython/commit/d851f8e258c7328814943e923a7df81bca15df4b
label: cna@python.org
- url: >-
https://github.com/python/cpython/commit/f3c6f882cddc8dc30320d2e73edf019e201394fc
label: cna@python.org
- url: >-
https://github.com/python/cpython/commit/fdc9d214c01cb4588f540cfa03726bbf2a33fc15
label: cna@python.org
- url: 'https://github.com/python/cpython/issues/135462'
label: cna@python.org
- url: 'https://github.com/python/cpython/pull/135464'
label: cna@python.org
- url: >-
https://mail.python.org/archives/list/security-announce@python.org/thread/K5PIYLR6EP3WR7ZOKKYQUWEDNQVUXOYM/
label: cna@python.org
- url: >-
https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-6069.json
- url: 'https://access.redhat.com/security/cve/CVE-2025-6069'
- url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2373234'
- url: 'https://www.cve.org/CVERecord?id=CVE-2025-6069'
- url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-6069'
- url: 'https://access.redhat.com/errata/RHSA-2025:23530'
- url: 'https://access.redhat.com/errata/RHSA-2026:74087'
- url: 'https://access.redhat.com/errata/RHSA-2025:23342'
- url: 'https://access.redhat.com/errata/RHSA-2026:1858'
- url: 'https://access.redhat.com/errata/RHSA-2026:1652'
- url: 'https://access.redhat.com/errata/RHSA-2026:0414'
- url: 'https://access.redhat.com/errata/RHSA-2026:0685'
- url: 'https://access.redhat.com/errata/RHSA-2026:76945'
tags:
- nvd
- csaf
- vex
- red-hat
epss: 0.00603
epssPercentile: 0.48651
ingestedAt: '2026-07-31T06:58:50.948Z'
vendor: Red Hat
product: Red Hat Enterprise Linux AppStream (v. 8)
affected:
- enterprise_linux 10
- enterprise_linux 6
- enterprise_linux 7
- enterprise_linux 8
- enterprise_linux 9
- enterprise_linux_ai_rhel_ai
- enterprise_linux_appstream_v_8
- enterprise_linux_appstream_e4s_v_9_4
- enterprise_linux_appstream_v_9
- enterprise_linux_baseos_e4s_v_9_4
- enterprise_linux_baseos_v_9
- enterprise_linux_crb_v_8
- enterprise_linux_codeready_linux_builder_v_9
- ceph_storage 7
- ceph_storage 8
- discovery 2
- update_infrastructure 5
patched:
- enterprise_linux_appstream_v_8
- enterprise_linux_appstream_e4s_v_9_4
- enterprise_linux_appstream_v_9
- enterprise_linux_baseos_e4s_v_9_4
- enterprise_linux_baseos_v_9
- enterprise_linux_crb_v_8
- enterprise_linux_codeready_linux_builder_v_9
- ceph_storage 7
- ceph_storage 8
- discovery 2
- update_infrastructure 5
---
## Overview
The html.parser.HTMLParser class had worse-case quadratic complexity when processing certain crafted malformed inputs potentially leading to amplified denial-of-service.
## Remediation
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
## Vendor advisories
- **RHSA-2025:23530** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2025-12-18 · [advisory](https://access.redhat.com/errata/RHSA-2025:23530)
- **RHSA-2026:74087** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.4), Red Hat Enterprise Linux BaseOS E4S (v.9.4) · released 2026-09-30 · [advisory](https://access.redhat.com/errata/RHSA-2026:74087)
- **RHSA-2025:23342** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) · released 2025-12-18 · [advisory](https://access.redhat.com/errata/RHSA-2025:23342)
- **RHSA-2026:1858** · Red Hat · fixed in: Red Hat Ceph Storage 7 · released 2026-02-03 · [advisory](https://access.redhat.com/errata/RHSA-2026:1858)
- **RHSA-2026:1652** · Red Hat · fixed in: Red Hat Ceph Storage 8 · released 2026-02-02 · [advisory](https://access.redhat.com/errata/RHSA-2026:1652)
- **RHSA-2026:0414** · Red Hat · fixed in: Red Hat Discovery 2 · released 2026-01-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:0414)
- **RHSA-2026:0685** · Red Hat · fixed in: Red Hat Update Infrastructure 5 · released 2026-01-15 · [advisory](https://access.redhat.com/errata/RHSA-2026:0685)
- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux AI (RHEL AI) · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-10-06 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-6069.json)
- **RHSA-2026:76945** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.2), Red Hat Enterprise Linux BaseOS E4S (v.9.2) · released 2026-10-06 · [advisory](https://access.redhat.com/errata/RHSA-2026:76945)