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CVE-2026-27459

pyOpenSSL DTLS cookie callback buffer overflow

CVSS 4.0 7.2 HIGHCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-27459

Published

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.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-27459

Published

pyopenssl

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "pyca",
                    "product": "pyopenssl",
                    "versions": [
                        {
                            "version": ">= 22.0.0, < 26.0.0",
                            "status": "affected"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON