PT-2026-56871 · Python · Cpython

Edward-X + 2 · Published 2026-07-09 · Updated 2026-07-09 · CVE-2026-15308

Mitre

CVSS v4.0

8.7

High

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

The incremental HTML parser (html.parser.HTMLParser) allows for CPU denial-of-service through repeated unterminated markup declarations when processing uncontrolled data.

Fix

Resource Exhaustion

Weakness Enumeration

CWE-400

Related Identifiers

CVE-2026-15308

Affected Products

Cpython

References · 8

• https://github.com/python/cpython/commit/07efb08123ba9367a7107325adb9d5626dca1ca9 · Patch
• https://github.com/python/cpython/commit/bcf98ddbc40ec9b3ee87da0124a5660b19b7e606 · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2026-15308 · Security Note
• https://mail.python.org/archives/list/[e-mail]/thread/F6453LWKSHKCTWFLCOURWPLETNUIW2Z5 · Vendor Advisory
• https://github.com/python/cpython/commit/e9f92ac0b298292e7ff998e52cb8ccacfb27a0bd · Patch
• https://github.com/python/cpython/commit/7933f4bf7131aa4140750f9404f5de0aa2969ced · Patch
• https://github.com/python/cpython/pull/153031 · Patch
• https://github.com/python/cpython/issues/153030 · Note