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Servers and applications

CVE-2026-15308

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

Severity
High 8.7
Published
9 Jul 2026
Last changed
20 Aug 2026
Added to UpHeron
21 Oct 2026
Fixed in
3.10.21, 3.11.16, 3.12.14, 3.13.15, 3.14.7
Sources
NVD

Affected software

SoftwareAffected versions
PythonServers and applications · cpe:a:python:python
  • Version 3.15.0-beta3
  • Version 3.15.0-beta2
  • Version 3.15.0-beta1
  • Version 3.15.0-alpha8
All 16 release lines
  • Every version before 3.10.21
  • From 3.11.0 before 3.11.16
  • From 3.12.0 before 3.12.14
  • From 3.13.0 before 3.13.15
  • From 3.14.0 before 3.14.7
  • Version 3.15.0-alpha1
  • Version 3.15.0-alpha2
  • Version 3.15.0-alpha3
  • Version 3.15.0-alpha4
  • Version 3.15.0-alpha5
  • Version 3.15.0-alpha6
  • Version 3.15.0-alpha7
  • Version 3.15.0-alpha8
  • Version 3.15.0-beta1
  • Version 3.15.0-beta2
  • Version 3.15.0-beta3

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2026-15308
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2026-15308