Resource exhaustion in Python
CVE-2026-15308
The incremental HTML parser (html.parser.HTMLParser) allows for CPU denial-of-service through repeated unterminated markup declarations when processing uncontrolled data.
Vulnerability class: DoS (Denial of Service)
EPSS: 0.006 (47.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Python — versions 3.15.0
- Python Software Foundation Cpython — versions 3.14.0, 0, 3.13.0
Weakness classification (CWE)
References
- cna@python.org (issue-tracking, Patch)
- cna@python.org (Patch, patch, Issue Tracking)
- cna@python.org (vendor-advisory, Mailing List)
- cna@python.org (Patch, patch)
- cna@python.org (Patch, patch)
- cna@python.org (Patch, patch)
- cna@python.org (Patch, patch)
- af854a3a-2127-422b-91ae-364da2661108 (Third Party Advisory)
- cna@python.org (Patch, patch)
- cna@python.org (Patch, patch)
Frequently asked questions
- What is CVE-2026-15308?
- CVE-2026-15308 is a high-severity vulnerability in Python, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-07-09.
- How severe is CVE-2026-15308?
- High severity. CVSS v3 base score is 7.5 out of 10.