CVE-2026-15308CWE-400denial-of-service

CVE-2026-15308

High · published July 9, 2026

CVSS v3.1
7.5
EPSS
1%
Percentile
49.9
In the wild
Unconfirmed
What it is

The incremental HTML parser (html.parser.HTMLParser) allows for CPU

denial-of-service through repeated unterminated markup declarations when

processing uncontrolled data.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00637 · 49.9th percentile
Weakness
CWE-400 · Uncontrolled Resource Consumption
Published
2026-07-09T21:16Z
Affected products (16)
ProductVersionsFixed in
python/python< 3.10.213.10.21
python/python≥ 3.11.0, < 3.11.163.11.16
python/python≥ 3.12.0, < 3.12.143.12.14
python/python≥ 3.13.0, < 3.13.153.13.15
python/python≥ 3.14.0, < 3.14.73.14.7
python/pythonall versions—
python/pythonall versions—
python/pythonall versions—
python/pythonall versions—
python/pythonall versions—
python/pythonall versions—
python/pythonall versions—
python/pythonall versions—
python/pythonall versions—
python/pythonall versions—
python/pythonall versions—
References (11)
https://github.com/python/cpython/commit/07efb08123ba9367a7107325adb9d5626dca1ca9 · [email protected]https://github.com/python/cpython/commit/1e7956f1a722df9aabc509c30f8fbdc3a2b4fdc7 · [email protected]https://github.com/python/cpython/commit/785df8f743800661961528970f8598edcd291c14 · [email protected]https://github.com/python/cpython/commit/7933f4bf7131aa4140750f9404f5de0aa2969ced · [email protected]https://github.com/python/cpython/commit/bcf98ddbc40ec9b3ee87da0124a5660b19b7e606 · [email protected]https://github.com/python/cpython/commit/c2390b9376e35a701ed3acc597b8fc87546c9b00 · [email protected]https://github.com/python/cpython/commit/e9f92ac0b298292e7ff998e52cb8ccacfb27a0bd · [email protected]https://github.com/python/cpython/issues/153030 · [email protected]https://github.com/python/cpython/pull/153031 · [email protected]https://mail.python.org/archives/list/[email protected]/thread/F6453LWKSHKCTWFLCOURWPLETNUIW2Z5/ · [email protected]http://www.openwall.com/lists/oss-security/2026/07/09/4 · af854a3a-2127-422b-91ae-364da2661108
EPSS history
Timeline
  • 09 JUL 17:10Z
    Incremental HTMLParser feed() allows CPU-exhaustion DoS via repeated unterminated markup declarations
    cvelistv5