Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-15308

Severity CVSS v4.0:
HIGH
Type:
CWE-400 Uncontrolled Resource Consumption ('Resource Exhaustion')
Publication date:
09/07/2026
Last modified:
20/08/2026

Description

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

Impact

Vector 4.0
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 CVSS v4.0 Severity and Metrics:

Base Score: 8.70 HIGH
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

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): None
Privileges Required (PR): None
User Interaction (UI): None
Confidentiality (VC): None
Integrity (VI): None
Availability (VA): High
Confidentiality (SC): None
Integrity (SI): None
Availability (SA): None

Base Score 4.0
8.70
Severity 4.0
HIGH
Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 7.50 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): None
Availability (A): High

Base Score 3.x
7.50
Severity 3.x
HIGH

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:python:python:*:*:*:*:*:*:*:* 3.10.21 (excluding)
cpe:2.3:a:python:python:*:*:*:*:*:*:*:* 3.11.0 (including) 3.11.16 (excluding)
cpe:2.3:a:python:python:*:*:*:*:*:*:*:* 3.12.0 (including) 3.12.14 (excluding)
cpe:2.3:a:python:python:*:*:*:*:*:*:*:* 3.13.0 (including) 3.13.15 (excluding)
cpe:2.3:a:python:python:*:*:*:*:*:*:*:* 3.14.0 (including) 3.14.7 (excluding)
cpe:2.3:a:python:python:3.15.0:alpha1:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha2:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha3:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha4:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha5:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha6:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha7:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha8:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:beta1:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:beta2:*:*:*:*:*:*

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools