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Vulnerability · Published Apr 10, 2026 · Assigned by PSF

CVE-2026-1502HTTP client proxy tunnel headers not validated for CR/LF

Medium 5.7

In plain English

A medium-severity security flaw in CPython from Python Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)5.7Medium
Exploit odds (30 days)0.6%top 53.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

CR/LF bytes were not rejected by HTTP client proxy tunnel headers or host.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:10python-unversioned-command3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:10python33.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:10python3-debug3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:10python3-devel3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:10python3-idle3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:10python3-libs3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:10python3-test3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:10python3-tkinter3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:8python3.123.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.123.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:8python3.12-debug3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.12-debug3.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:8python3.12-devel3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.12-devel3.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:8python3.12-idle3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.12-idle3.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:8python3.12-libs3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.12-libs3.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:8python3.12-rpm-macros3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:8python3.12-test3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.12-test3.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:8python3.12-tkinter3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.12-tkinter3.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:10python3.143.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.143.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-debug3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-debug3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-devel3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-devel3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-freethreading3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-freethreading3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-freethreading-debug3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-freethreading-debug3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-freethreading-devel3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-freethreading-devel3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-freethreading-idle3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-freethreading-idle3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-freethreading-libs3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-freethreading-libs3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-freethreading-test3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-freethreading-test3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-freethreading-tkinter3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-freethreading-tkinter3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-idle3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-idle3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-libs3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-libs3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-test3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-test3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-tkinter3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-tkinter3.14.4-2.el9_8ALSA-2026:19176
Alpine:v3.21python33.12.14-r0ALPINE-CVE-2026-1502
Alpine:v3.22python33.12.14-r0ALPINE-CVE-2026-1502
Alpine:v3.23python33.12.14-r0ALPINE-CVE-2026-1502
Debian:12pypy3no fix listedDEBIAN-CVE-2026-1502
Debian:13pypy3no fix listedDEBIAN-CVE-2026-1502
Debian:14pypy37.3.22+dfsg-1DEBIAN-CVE-2026-1502
Debian:12python3.113.11.2-6+deb12u9DEBIAN-CVE-2026-1502
Debian:13python3.133.13.5-2+deb13u3DEBIAN-CVE-2026-1502
Debian:14python3.143.14.5-1DEBIAN-CVE-2026-1502
Rocky Linux:10python3.120:3.12.13-2.el10_2RLSA-2026:19064
Rocky Linux:8python3.120:3.12.13-2.el8_10RLSA-2026:10950
Rocky Linux:9python3.120:3.12.13-2.el9_8RLSA-2026:19177
Rocky Linux:10python3.140:3.14.4-2.el10_2RLSA-2026:19019
Rocky Linux:9python3.140:3.14.4-2.el9_8RLSA-2026:19176
Ubuntu:22.04:LTSjythonno fix listedUBUNTU-CVE-2026-1502
Ubuntu:24.04:LTSjythonno fix listedUBUNTU-CVE-2026-1502
Ubuntu:25.10jythonno fix listedUBUNTU-CVE-2026-1502
Ubuntu:26.04:LTSjythonno fix listedUBUNTU-CVE-2026-1502
Ubuntu:26.10jythonno fix listedUBUNTU-CVE-2026-1502
Ubuntu:22.04:LTSpypy3no fix listedUBUNTU-CVE-2026-1502
Ubuntu:24.04:LTSpypy3no fix listedUBUNTU-CVE-2026-1502
Ubuntu:25.10pypy3no fix listedUBUNTU-CVE-2026-1502
Ubuntu:26.04:LTSpypy3no fix listedUBUNTU-CVE-2026-1502
Ubuntu:26.10pypy3no fix listedUBUNTU-CVE-2026-1502
Ubuntu:22.04:LTSpython3.103.10.12-1~22.04.16USN-8509-1
Ubuntu:22.04:LTSpython3.103.10.12-1~22.04.16UBUNTU-CVE-2026-1502
Ubuntu:24.04:LTSpython3.123.12.3-1ubuntu0.15USN-8509-1
Ubuntu:24.04:LTSpython3.123.12.3-1ubuntu0.15UBUNTU-CVE-2026-1502
Ubuntu:25.10python3.13no fix listedUBUNTU-CVE-2026-1502
Ubuntu:25.10python3.14no fix listedUBUNTU-CVE-2026-1502
Ubuntu:26.04:LTSpython3.143.14.4-1ubuntu0.1UBUNTU-CVE-2026-1502
Ubuntu:26.04:LTSpython3.143.14.4-1ubuntu0.1USN-8509-1

Affected products (as reported)

VendorProductVersions
Python Software Foundation CPython 0 – before 3.10.213.11.0 – before 3.11.163.12.0 – before 3.12.143.13.0 – before 3.13.143.14.0a1 – before 3.14.5rc13.15.0a1 – before 3.15.0b1

Weakness: CWE-93 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

References