Is CVE-2026-27459 actively exploited?

CVE-2026-27459 has no public evidence of in-the-wild exploitation as of 2026-03-18.

What is the CVSS score for CVE-2026-27459?

CVE-2026-27459 has a CVSS score of 7.2 (HIGH severity). Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/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.

How do I patch CVE-2026-27459?

Vendor patch guidance is linked from the references on this page. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2026-27459.

Which products are affected by CVE-2026-27459?

Affected products for CVE-2026-27459 are listed on this page once vendor data becomes available.

Fix CVE-2026-27459 - HIGH Vulnerability

Description

pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 22.0.0 and prior to version 26.0.0, if a user provided callback to `set_cookie_generate_callback` returned a cookie value greater than 256 bytes, pyOpenSSL would overflow an OpenSSL provided buffer. Starting in version 26.0.0, cookie values that are too long are now rejected.

CVSS Metrics

Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/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
Attack Vector: network
Complexity: high
Privileges: none
User Action: none
Confidentiality: undefined
Integrity: undefined
Availability: undefined
Weaknesses: CWE-120

Metadata

Primary Vendor: UNKNOWN
Published: 3/18/2026
Last Modified: 3/18/2026
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

CVE-2026-27459

Description

CVSS Metrics

Metadata

Affected Products

Remediation Guidance

Executive Summary