CVE-2026-15308 | The incremental HTML parser (html.parser.HTMLParser) allows … | CVSS 8.7 HIGH

Description

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

Metadata

CVE ID: CVE-2026-15308
State: PUBLISHED
Assigner: PSF
Reserved: 2026-07-09 17:04 UTC
Published: 2026-07-09 17:10 UTC
Last updated: 2026-07-09 19:32 UTC
Primary CWE: CWE-400
CWE-400
Vendor / Product: Python Software Foundation / CPython
Sources: cve.org · NVD

Severity & Metrics

8.7 HIGH CVSS 4.0

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

SSVC — CISA Coordinator

Exploitation: none
Automatable: yes
Tech. Impact: partial

Affected products (1)

Vendor	Product	Platform	Versions
Python Software Foundation	CPython	—	0 < 3.15.0

Weakness (CWE)

CWE	Source	Description
CWE-400	cna	CWE-400

CVSS scores (1)

Score	Severity	Version	Source	Vector
8.7	HIGH	4.0	cna	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References (7)