Buffer overflow in pyopenssl - CVE-2026-27459

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Main Vulnerability Database Vulnerabilities #VU144104

Buffer overflow in pyopenssl - CVE-2026-27459

Published: August 18, 2026


Vulnerability identifier: #VU144104
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-27459
CWE-ID: CWE-120
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists because the callback provided to `set_cookie_generate_callback` returned a cookie value greater than 256 bytes, causing pyOpenSSL to overflow an OpenSSL-provided buffer. A remote attacker can pass specially crafted data to the application, trigger a buffer overflow and execute arbitrary code on the target system.


Affected software

pyopenssl
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
SUSE Liberty Linux 9.6
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Desktop 12
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing 12
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Manager Server
SUSE Manager Retail Branch Server
SUSE Manager Proxy
SUSE Manager Client Tools for SLE Micro
SUSE Linux Enterprise Micro
SUSE Linux Micro
SUSE Manager Client Tools for RHEL, Liberty and Clones
SUSE Manager Client Tools for Debian
SUSE Manager Client Tools for SLE
SUSE Linux Enterprise Server for the Raspberry Pi
SUSE Linux Enterprise Server
SUSE Linux Enterprise Server for SAP Applications
SUSE Linux Enterprise Desktop
SUSE Linux Enterprise High Performance Computing
Public Cloud Module
Python 3 Module
openSUSE Leap
Ubuntu
Anolis OS
openEuler
Fedora
SUSE Manager Client Tools for Ubuntu 22.04
SUSE Manager Client Tools for Ubuntu 24.04
DataStage on Cloud Pak for Data
Storage Protect Plus File Systems Agent
Storage Protect Plus Guest Applications
rust-cryptoki-sys
rust-wycheproof
rust-cryptoki
rust-asn1
rust-asn1_derive
kryoptic
pyopenssl (Ubuntu package)
python311-pyOpenSSL
pyOpenSSL-help
python3-pyOpenSSL
pyOpenSSL
python3-pyOpenSSL-doc
python-cryptography
venv-salt-minion
IBM Cloud Pak for Data System

How to mitigate CVE-2026-27459

Install updates from vendor's website.

pyopenssl - update to 26.1.0
DataStage on Cloud Pak for Data - addressed in versions 5.3.1 patch 6, 5.4 patch 5
Storage Protect Plus File Systems Agent - update to 10.1.19
Storage Protect Plus Guest Applications - update to 10.1.19
rust-cryptoki-sys - update to 0.5.0-2.fc43
rust-wycheproof - update to 0.6.0-1.fc43
rust-cryptoki - update to 0.12.0-2.fc43
rust-asn1 - update to 0.22.0-1.fc43
rust-asn1_derive - update to 0.22.0-1.fc43
kryoptic - update to 1.5.0-2.fc43
IBM Cloud Pak for Data System - update to 8.10.26.06.SP2
pyopenssl (Ubuntu package) - addressed in versions 21.0.0-1ubuntu0.1, 23.2.0-1ubuntu0.1, 25.0.0-1ubuntu0.1
python311-pyOpenSSL - addressed in versions 23.2.0-150400.3.13.1, 24.0.0-2.1
pyOpenSSL-help - update to 24.0.0-3
python3-pyOpenSSL - update to 24.0.0-3
pyOpenSSL - update to 24.0.0-3
python3-pyOpenSSL-doc - update to 24.1.0-2
python3-pyOpenSSL - update to 24.1.0-2
pyOpenSSL - addressed in versions 26.0.0-1.fc43, 26.0.0-1.fc44
python-cryptography - update to 46.0.5-1.fc43
venv-salt-minion - addressed in versions 3006.0-1.76.1, 3006.0-2.31.2, 3006.0-2.49.2, 3006.0-2.80.1, 3006.0-3.95.1, 3006.0-150000.3.95.1

External References

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