| Name | CVE-2026-15308 |
| Description | The incremental HTML parser (html.parser.HTMLParser) allows for CPU denial-of-service through repeated unterminated markup declarations when processing uncontrolled data. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|
| python2.7 (PTS) | bullseye | 2.7.18-8+deb11u1 | vulnerable |
| python3.11 (PTS) | bookworm | 3.11.2-6+deb12u8 | vulnerable |
| bookworm (security) | 3.11.2-6+deb12u3 | vulnerable |
| python3.13 (PTS) | trixie | 3.13.5-2+deb13u3 | vulnerable |
| forky, sid | 3.13.14-1 | vulnerable |
| python3.14 (PTS) | forky, sid | 3.14.6-1 | vulnerable |
| python3.9 (PTS) | bullseye | 3.9.2-1 | vulnerable |
| bullseye (security) | 3.9.2-1+deb11u7 | vulnerable |
The information below is based on the following data on fixed versions.
Notes
[bookworm] - python3.11 <postponed> (CPU-only DoS; the quadratic rescan needs feed() driven in small chunks, a single feed() of the whole document stays linear; no upstream fix for this branch)
[bullseye] - python3.9 <postponed> (CPU-only DoS; the quadratic rescan needs feed() driven in small chunks, a single feed() of the whole document stays linear; no upstream fix for this branch)
[bullseye] - python2.7 <end-of-life> (EOL in bullseye LTS)
https://mail.python.org/archives/list/security-announce@python.org/thread/F6453LWKSHKCTWFLCOURWPLETNUIW2Z5/
https://github.com/python/cpython/issues/153030
https://github.com/python/cpython/pull/153031
https://github.com/python/cpython/commit/e9f92ac0b298292e7ff998e52cb8ccacfb27a0bd (v3.15.0b4)
https://github.com/python/cpython/commit/07efb08123ba9367a7107325adb9d5626dca1ca9 (3.14 branch)
https://github.com/python/cpython/commit/7933f4bf7131aa4140750f9404f5de0aa2969ced (3.13 branch)