Name: CVE-2026-15308: Uncontrolled Resource Consumption
Creator: Rapid7
Published: 2026-07-09T00:00:00.000Z
License: https://www.rapid7.com/legal/website-terms-of-use/
Keywords: CVE, CVE-2026-15308, CWE-400, CVSS 7.5, EPSS 0.00637

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

CVSS Details

CVSS 4.0 Base Score: 8.7 (HIGH)
CVSS 4.0 Vector: (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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X)
CVSS 3.1 Base Score: 7.5
CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Covered by Rapid7

Product	Vendor Advisory	Solution File	Added	Published
Alma_linux	—	Upgrade python3.14-develUpgrade platform-python-develUpgrade python3.14-idleUpgrade python3.14-freethreading-debugUpgrade python3-libsUpgrade python3.12-idleUpgrade python3.14-debugUpgrade python3.12-develUpgrade platform-python-debugUpgrade python-unversioned-commandUpgrade python3.14-tkinterUpgrade python3-idleUpgrade platform-pythonUpgrade python3.12-testUpgrade python3.14-freethreading-develUpgrade python3Upgrade python3-tkinterUpgrade python3-develUpgrade python3-debugUpgrade python3.14-freethreadingUpgrade python3.12-debugUpgrade python3.12Upgrade python3.12-rpm-macrosUpgrade python3.14Upgrade python3-testUpgrade python3.14-freethreading-idleUpgrade python3.14-libsUpgrade python3.12-libsUpgrade python3.12-tkinterUpgrade python3.14-freethreading-tkinterUpgrade python3.14-testUpgrade python3.14-freethreading-libsUpgrade python3.14-freethreading-test	Jul 15, 2026	Jul 14, 2026
Alpine Linux	—	Upgrade python3	Aug 17, 2026	Jul 9, 2026
Amazon Linux Ami 2	—	Upgrade pythonUpgrade python-debugUpgrade tkinterUpgrade python-testUpgrade python3-testUpgrade python3-debuginfoUpgrade python3-libsUpgrade python3-tkinterUpgrade python-develUpgrade python3-debugUpgrade python3-toolsUpgrade python-toolsUpgrade python3-develUpgrade python3Upgrade python-libsUpgrade python-debuginfo	Aug 5, 2026	Aug 5, 2026
Amazon_linux_2023	—	Upgrade python3.12-idleUpgrade python3.14-libsUpgrade python3.14-freethreading-idleUpgrade python3-debugUpgrade python3.14-develUpgrade python3.13-debuginfoUpgrade python3.14-idleUpgrade python3.14-freethreadingUpgrade python3-testUpgrade python3.12Upgrade python3.12-debuginfoUpgrade python3Upgrade python3.12-tkinterUpgrade python3.13-develUpgrade python3.12-debugUpgrade python3.14-tkinterUpgrade python3.14-debuginfoUpgrade python3.14-debugsourceUpgrade python3.14-freethreading-tkinterUpgrade python3.12-libsUpgrade python3.13-debugsourceUpgrade python3.14-freethreading-testUpgrade python3.14-debugUpgrade python-unversioned-commandUpgrade python3.12-develUpgrade python3-idleUpgrade python3.14-freethreading-debugUpgrade python3.12-testUpgrade python3.13-freethreadingUpgrade python3.13-freethreading-debugUpgrade python3.14-freethreading-develUpgrade python3.13-testUpgrade python3.13-libsUpgrade python3-libsUpgrade python3.13Upgrade python3.9-debuginfoUpgrade python3.14-freethreading-libsUpgrade python3.14Upgrade python3.14-testUpgrade python3.13-tkinterUpgrade python3.13-debugUpgrade python3-tkinterUpgrade python3-develUpgrade python3.9-debugsourceUpgrade python3.13-idleUpgrade python3.12-debugsource	Aug 10, 2026	Jul 9, 2026
Debian	—	Upgrade python3.11	Oct 12, 2026	Jul 9, 2026
Ibm Aix	—	Apply the fix or workaround for python_advisory21	Sep 15, 2026	Sep 15, 2026
Redhat_linux	—	Upgrade python3.14-freethreading-libsUpgrade python3.12-rpm-macrosUpgrade platform-pythonUpgrade python3.12-tkinterUpgrade python3.14-develUpgrade python3.12-debugsourceUpgrade python3.9-debugsourceUpgrade python3.12-develUpgrade python-unversioned-commandUpgrade python3.14-freethreading-testUpgrade python3.14-freethreading-develUpgrade python3.12Upgrade python3.14Upgrade python3.14-debuginfoUpgrade python3-tkinterUpgrade python3-testUpgrade python3.14-testUpgrade python3.14-debugsourceUpgrade python3.14-debugUpgrade python3Upgrade python3-libsUpgrade python3.12-idleUpgrade python3-idleUpgrade python3.12-debugUpgrade python3-debuginfoUpgrade python3.14-freethreadingUpgrade python3.12-testNo solution existsUpgrade python3-debugUpgrade platform-python-develUpgrade python3.14-freethreading-debugUpgrade python3.14-freethreading-idleUpgrade python3.14-freethreading-tkinterUpgrade python3.12-debuginfoUpgrade python3.14-tkinterUpgrade python3.14-libsUpgrade platform-python-debugUpgrade python3.14-idleUpgrade python3.12-libsUpgrade python3-debugsourceUpgrade python3-develUpgrade python3.9-debuginfo	Jul 15, 2026	Jul 9, 2026
Rocky_linux	—	Upgrade python3-debugsourceUpgrade python3.14-freethreadingUpgrade python3Upgrade python3-libsUpgrade python3-tkinterUpgrade python3-debuginfoUpgrade python3-idleUpgrade python3.12-debugUpgrade python3.14-libsUpgrade python3.14-idleUpgrade python3.14-debugUpgrade python3.12-libsUpgrade python3.9-debuginfoUpgrade python3.14-freethreading-debugUpgrade python3.14-freethreading-tkinterUpgrade python3-develUpgrade platform-python-develUpgrade python3-debugUpgrade python3.12-testUpgrade python3.14-tkinterUpgrade platform-python-debugUpgrade python3.12Upgrade python3-testUpgrade python3.14-freethreading-idleUpgrade python3.12-debugsourceUpgrade python3.12-debuginfoUpgrade python3.14Upgrade platform-pythonUpgrade python3.12-develUpgrade python3.9-debugsourceUpgrade python3.14-freethreading-develUpgrade python3.14-debuginfoUpgrade python3.14-debugsourceUpgrade python3.14-freethreading-testUpgrade python3.14-develUpgrade python3.12-idleUpgrade python3.12-tkinterUpgrade python3.14-freethreading-libsUpgrade python3.14-test	Jul 17, 2026	Jul 16, 2026
Ubuntu	—	Upgrade libpython3.11 (Ubuntu Pro)Upgrade libpython3.5 (Ubuntu Pro)Upgrade libpython3.14Upgrade python3.12Upgrade python3.6 (Ubuntu Pro)Upgrade python3.4 (Ubuntu Pro)Upgrade python3.8 (Ubuntu Pro)Upgrade libpython3.8 (Ubuntu Pro)Upgrade libpython3.4 (Ubuntu Pro)Upgrade python3.10Upgrade libpython3.9 (Ubuntu Pro)Upgrade python3.5 (Ubuntu Pro)Upgrade libpython2.7 (Ubuntu Pro)Upgrade libpython3.7 (Ubuntu Pro)Upgrade python3.7 (Ubuntu Pro)Upgrade python3.9 (Ubuntu Pro)Upgrade libpython3.10Upgrade python2.7 (Ubuntu Pro)Upgrade libpython3.6 (Ubuntu Pro)Upgrade python3.11 (Ubuntu Pro)Upgrade libpython3.12t64Upgrade python3.14	Sep 14, 2026	Sep 10, 2026
Vmware Photon_os	—	Use 'tdnf update' to upgrade all packages to the latest version.	Aug 20, 2026	Jul 9, 2026

Prioritise with Active Threat Intelligence

With curated Threat Intelligence, you can see which vulnerabilities truly put you at risk, prioritize what matters most, and act before attackers do.

Explore Intelligence Hub

MDR Buyer's Guide

Global Threat Landscape Report

Grow your business

CVSS Details

Covered by Rapid7

Prioritise with Active Threat Intelligence