CVE-2026-27459
pyOpenSSL DTLS cookie callback buffer overflow
- State
- Published
- Severity
- 7.2 High
- Published
- Mar 17, 2026
- Updated
- Sep 11, 2026
- Reserved
- Feb 19, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 7.2 High | 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 | GitHub_M |
| 3.1 | 8.1 High | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H | redhat-SADP |
Weaknesses
- CWE-120 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Affected Products
| Product | Versions |
|---|---|
pyopensslpyca |
|
References
- https://github.com/pyca/pyopenssl/security/advisories/GHSA-5pwr-322w-8jr4
- https://github.com/pyca/pyopenssl/commit/57f09bb4bb051d3bc2a1abd36e9525313d5cd408
- https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst
- https://access.redhat.com/security/cve/CVE-2026-27459vdb-entry
- RHBZ#2448503issue-tracking
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27459.json
- https://access.redhat.com/errata/RHSA-2026:13512vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:10754vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:14874vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:13508vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:14873vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:14835vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:13553vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:13545vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:59153vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:48758vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:7224vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:11916vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:11856vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:21017vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:24853vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:19375vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:22465vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:48085vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:11996vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:8437vendor-advisory
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