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CVE-2025-6069HTMLParser quadratic complexity when processing malformed inputs
- 4.3MediumCVSS base score
- 0.60%Exploitation in 30 daysEPSS · top 51% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
The html.parser.HTMLParser class had worse-case quadratic complexity when processing certain crafted malformed inputs potentially leading to amplified denial-of-service.
Timeline
ID reserved
By PSF
- 4 days later
· 4 days later
Published
- 14 months later
· 14 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| PSFCNA (assigner) | 3.1 | Medium4.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L |
| NVDNVD · Deferred | 3.1 | Medium4.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L |
- EPSS (exploitation in 30 days)
- 0.60% · top 51% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.3.
Affected products
Python Software Foundation · CPython
- affected < 3.9.24
- affected 3.10.0 – < 3.10.19
- affected 3.11.0 – < 3.11.14
- affected 3.12.0 – < 3.12.12
- affected 3.13.0 – < 3.13.6
- affected 3.14.0a1 – < 3.14.0b3
References
References10
- https://github.com/python/cpython/issues/135462 (opens in a new tab)issue-tracking
- https://github.com/python/cpython/pull/135464 (opens in a new tab)patch
- https://github.com/python/cpython/commit/4455cbabf991e202185a25a631af206f60bbc949 (opens in a new tab)patch
- https://github.com/python/cpython/commit/6eb6c5dbfb528bd07d77b60fd71fd05d81d45c41 (opens in a new tab)patch
- https://github.com/python/cpython/commit/d851f8e258c7328814943e923a7df81bca15df4b (opens in a new tab)patch
- https://mail.python.org/archives/list/[email protected]/thread/K5PIYLR6EP3WR7ZOKKYQUWEDNQVUXOYM/ (opens in a new tab)vendor-advisory
- https://github.com/python/cpython/commit/8d1b3dfa09135affbbf27fb8babcf3c11415df49 (opens in a new tab)patch
- https://github.com/python/cpython/commit/ab0893fd5c579d9cea30841680e6d35fc478afb5 (opens in a new tab)patch
- https://github.com/python/cpython/commit/f3c6f882cddc8dc30320d2e73edf019e201394fc (opens in a new tab)patch
- https://github.com/python/cpython/commit/fdc9d214c01cb4588f540cfa03726bbf2a33fc15 (opens in a new tab)patch
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2025-18496 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2025-6069)Record last updated .