🔐 CVE Alert

CVE-2026-15308

UNKNOWN 0.0

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

CVSS Score
0.0
EPSS Score
0.6%
EPSS Percentile
47th

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

CWE CWE-400
Vendor python software foundation
Product cpython
Published Jul 9, 2026
Last Updated Aug 13, 2026
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Affected Versions

Python Software Foundation / CPython
0 < 3.10.21 3.11.0 < 3.11.16 3.12.0 < 3.12.14 3.13.0 < 3.13.15 3.14.0 < 3.14.7 3.15.0a1 < 3.15.0b4

References

NVD ↗ CVE.org ↗ EPSS Data ↗
mail.python.org: https://mail.python.org/archives/list/[email protected]/thread/F6453LWKSHKCTWFLCOURWPLETNUIW2Z5/ github.com: https://github.com/python/cpython/pull/153031 github.com: https://github.com/python/cpython/issues/153030 github.com: https://github.com/python/cpython/commit/07efb08123ba9367a7107325adb9d5626dca1ca9 github.com: https://github.com/python/cpython/commit/7933f4bf7131aa4140750f9404f5de0aa2969ced github.com: https://github.com/python/cpython/commit/bcf98ddbc40ec9b3ee87da0124a5660b19b7e606 github.com: https://github.com/python/cpython/commit/e9f92ac0b298292e7ff998e52cb8ccacfb27a0bd github.com: https://github.com/python/cpython/commit/785df8f743800661961528970f8598edcd291c14 github.com: https://github.com/python/cpython/commit/1e7956f1a722df9aabc509c30f8fbdc3a2b4fdc7 github.com: https://github.com/python/cpython/commit/c2390b9376e35a701ed3acc597b8fc87546c9b00 openwall.com: http://www.openwall.com/lists/oss-security/2026/07/09/4

Credits

🔍 Edward-x (https://github.com/YLChen-007) Serhiy Storchaka (https://github.com/serhiy-storchaka) Gregory P. Smith (https://github.com/gpshead) Seth Larson (https://github.com/sethmlarson)