Vulnerability in Python Software Foundation Cpython
CVE-2025-6069
The html.parser.HTMLParser class had worse-case quadratic complexity when processing certain crafted malformed inputs potentially leading to amplified denial-of-service.
Vulnerability class: ReDoS (Regular Expression Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.006 (46.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 46.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001
Affected products
- Python Software Foundation Cpython — versions 3.10.0, 0, 3.14.0a1
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/python/cpython/issues/135462 (issue-tracking)
- github.com/python/cpython/pull/135464 (patch)
- github.com/python/cpython/commit/4455cbabf991e202185a25a631af206f60bbc949 (patch)
- github.com/python/cpython/commit/6eb6c5dbfb528bd07d77b60fd71fd05d81d45c41 (patch)
- github.com/python/cpython/commit/d851f8e258c7328814943e923a7df81bca15df4b (patch)
- mail.python.org/archives/list/security-announce@python.org/thread/K5PIYLR6EP3WR… (vendor-advisory)
- github.com/python/cpython/commit/8d1b3dfa09135affbbf27fb8babcf3c11415df49 (patch)
- github.com/python/cpython/commit/ab0893fd5c579d9cea30841680e6d35fc478afb5 (patch)
- github.com/python/cpython/commit/f3c6f882cddc8dc30320d2e73edf019e201394fc (patch)
- github.com/python/cpython/commit/fdc9d214c01cb4588f540cfa03726bbf2a33fc15 (patch)
Frequently asked questions
- What is CVE-2025-6069?
- CVE-2025-6069 is a medium-severity vulnerability in Python Software Foundation Cpython, classified under Inefficient Regular Expression Complexity. CVSS score: 4.3/10. Published 2025-06-17.
- How severe is CVE-2025-6069?
- Medium severity. CVSS v3 base score is 4.3 out of 10.
- Is CVE-2025-6069 known to be exploited?
- 4 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.