CVE-2026-15308
published 2026-07-09CVE-2026-15308: The incremental HTML parser (html.parser.HTMLParser) allows for CPU denial-of-service through repeated unterminated markup declarations when processing…
PriorityP340high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
0.64%
49.9th percentile
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Affected
49 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| ansible-automation-platform | bootc-automation-portal-rhel9 | — | — |
| container-native-virtualization | ocp-virt-validation-checkup-rhel9 | — | — |
| debian | python3.11 | — | — |
| debian | python3.13 | — | — |
| debian | python3.14 | — | — |
| debian | python3.9 | — | — |
| exploit-intelligence-tech-preview | vulnerability-analysis-rhel9 | — | — |
| python | python | < 3.10.21 | 3.10.21 |
| python | python | — | — |
| python | python | — | — |
| python | python | — | — |
| python | python | — | — |
| python | python | — | — |
| python | python | — | — |
| python | python | — | — |
| python | python | — | — |
| python | python | — | — |
| python | python | — | — |
| python | python | — | — |
| python | python | — | — |
| python | python | >= 3.11.0 < 3.11.16 | 3.11.16 |
| python | python | >= 3.12.0 < 3.12.14 | 3.12.14 |
| python | python | >= 3.13.0 < 3.13.15 | 3.13.15 |
| python | python | >= 3.14.0 < 3.14.7 | 3.14.7 |
| python36_3.6 | python36 | — | — |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvdv4.08.7HIGHCVSS: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
vendor_redhat8.7HIGH
vendor_ubuntu7.5HIGH
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Ubuntu
Python vulnerabilities
vendor_ubuntu·2026-09-10·CVSS 7.5
CVE-2026-3644 [HIGH] Python vulnerabilities
Title: Python vulnerabilities
Summary: Several security issues were fixed in Python.
It was discovered that Python's http.cookies module incorrectly handled
control characters in certain cookie operations. An attacker could possibly
use this issue to inject arbitrary content. This issue only affected
Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, Ubuntu 20.04 LTS,
Ubuntu 22.04 LTS and Ubuntu 24.04 LTS. (CVE-2026-3644)
It was discovered that the Python pyexpat module was vulnerable to
unbounded recursion in the Expat XML parser. An attacker could possibly use
this issue to cause Python to crash, resulting in a denial of service. This
issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, Ubuntu 18.04 LTS,
Ubuntu 20.04 LTS, Ubuntu 22.04 LTS and Ubuntu 24.04 LTS. (CVE-2026-4224)
I
Red Hat
python: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations
vendor_redhat·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CWE-835 python: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations
python: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations
A flaw was found in Python. Its incremental HTML parser can be exploited by a remote attacker. By sending specially crafted, uncontrolled data with repeated, incomplete markup declarations, the attacker can cause the system to consume excessive central processing unit (CPU) resources. This leads to a denial of service, making the affected system unresponsive.
Statement: This Important vulnerability in Python's `html.parser.HTMLParser` can lead to a denial of service. By supplying specially crafted, malformed HTML with repeated unterminated markup declarations, an attacker can cause excessive CPU consumption, rendering the system unresponsive. Red Hat products utilizing this parser to proces
VulDB
Python up to 3.14.x Incremental HTML Parser HTMLParser denial of service (EUVD-2026-42638 / Nessus ID 326073)
vuldb·2026-10-12·CVSS 7.5
CVE-2026-15308 [HIGH] Python up to 3.14.x Incremental HTML Parser HTMLParser denial of service (EUVD-2026-42638 / Nessus ID 326073)
A vulnerability marked as problematic has been reported in Python up to 3.14.x. The impacted element is the function HTMLParser of the component Incremental HTML Parser. Performing a manipulation results in denial of service.
This vulnerability is identified as CVE-2026-15308. The attack can be initiated remotely. There is not any exploit available.
It is suggested to upgrade the affected component.
GHSA
The incremental HTML parser (html.parser.HTMLParser) allows for CPU denial-of-service through repeated unterminated markup declarations when processing uncontrolled data.
ghsa_unreviewed·2026-07-09
CVE-2026-15308 [CRITICAL] CWE-400 The incremental HTML parser (html.parser.HTMLParser) allows for CPU denial-of-service through repeated unterminated markup declarations when processing uncontrolled data.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-15308 python3.13: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 python3.13: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
CVE-2026-15308 python3.13: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Bugzilla
CVE-2026-15308 python3.9: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 python3.9: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
CVE-2026-15308 python3.9: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Bugzilla
CVE-2026-15308 python3.15: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 python3.15: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
CVE-2026-15308 python3.15: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Bugzilla
CVE-2026-15308 python3.10: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 python3.10: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
CVE-2026-15308 python3.10: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Bugzilla
CVE-2026-15308 python3.11: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 python3.11: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
CVE-2026-15308 python3.11: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Bugzilla
CVE-2026-15308 asahi-installer: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 asahi-installer: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
CVE-2026-15308 asahi-installer: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Bugzilla
CVE-2026-15308 python3.13: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [epel-all]
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 python3.13: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [epel-all]
CVE-2026-15308 python3.13: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [epel-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Bugzilla
CVE-2026-15308 python3.6: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 python3.6: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
CVE-2026-15308 python3.6: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Bugzilla
CVE-2026-15308 python3.12: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 python3.12: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
CVE-2026-15308 python3.12: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Bugzilla
CVE-2026-15308 python: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 python: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations
CVE-2026-15308 python: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Bugzilla
CVE-2026-15308 mingw-python3: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 mingw-python3: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
CVE-2026-15308 mingw-python3: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Bugzilla
CVE-2026-15308 python3.14: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 python3.14: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
CVE-2026-15308 python3.14: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
Bugzilla
CVE-2026-15308 asahi-installer: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [epel-all]
bugzilla·2026-07-09·CVSS 8.7
CVE-2026-15308 [HIGH] CVE-2026-15308 asahi-installer: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [epel-all]
CVE-2026-15308 asahi-installer: Python: CPU Denial of Service in HTML parser via repeated unterminated markup declarations [epel-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
The incremental HTML parser (html.parser.HTMLParser) allows for CPU
denial-of-service through repeated unterminated markup declarations when
processing uncontrolled data.
https://github.com/python/cpython/commit/07efb08123ba9367a7107325adb9d5626dca1ca9https://github.com/python/cpython/commit/1e7956f1a722df9aabc509c30f8fbdc3a2b4fdc7https://github.com/python/cpython/commit/785df8f743800661961528970f8598edcd291c14https://github.com/python/cpython/commit/7933f4bf7131aa4140750f9404f5de0aa2969cedhttps://github.com/python/cpython/commit/bcf98ddbc40ec9b3ee87da0124a5660b19b7e606https://github.com/python/cpython/commit/c2390b9376e35a701ed3acc597b8fc87546c9b00https://github.com/python/cpython/commit/e9f92ac0b298292e7ff998e52cb8ccacfb27a0bdhttps://github.com/python/cpython/issues/153030https://github.com/python/cpython/pull/153031https://mail.python.org/archives/list/[email protected]/thread/F6453LWKSHKCTWFLCOURWPLETNUIW2Z5/http://www.openwall.com/lists/oss-security/2026/07/09/4
2026-07-09
Published