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CVE-2026-15308

Incremental HTMLParser feed() allows CPU-exhaustion DoS via repeated unterminated markup declarations

Published: Jul 9, 2026Updated: Aug 6, 2026 Sources: CVE List NVDCWE-400
7.5HIGH
NVD MITRE
EPSS Score
0.6%
Top 53.6%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

Description

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

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-400NVD-CWE-noinfo

Affected Products

Python Software Foundation
oss-project·USaka psf
CPython
OSS Libraries
python
oss-project·US
pythonLibraryLibrary
OSS Libraries

Exploitability

Official Patch Available
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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

https://mail.python.org/archives/list/security-announce@python.org/thread/F6453LWKSHKCTWFLCOURWPLETNUIW2Z5/
mail.python.org
https://github.com/python/cpython/pull/153031
github.com
https://github.com/python/cpython/issues/153030
github.com
and 6 more references View all →

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