CVE-2026-27459pyOpenSSL is a Python wrapper around the OpenSSL library.
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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
- 9.8 CRITICAL (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-120
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Modified
- Record last updated
- Sep 10, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
pyopenssl pyopenssl pyopenssl:pyopenssl | from 22.0.0 before 26.0.0 | NVD |
References
- https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rstrelease-notes
- https://github.com/pyca/pyopenssl/commit/57f09bb4bb051d3bc2a1abd36e9525313d5cd408patch
- https://github.com/pyca/pyopenssl/security/advisories/GHSA-5pwr-322w-8jr4vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:10754
- https://access.redhat.com/errata/RHSA-2026:11856
- https://access.redhat.com/errata/RHSA-2026:11916
- https://access.redhat.com/errata/RHSA-2026:11996
- https://access.redhat.com/errata/RHSA-2026:13508
- https://access.redhat.com/errata/RHSA-2026:13512
- https://access.redhat.com/errata/RHSA-2026:13545
- https://access.redhat.com/errata/RHSA-2026:13553
- https://access.redhat.com/errata/RHSA-2026:14835
- https://access.redhat.com/errata/RHSA-2026:14873
- https://access.redhat.com/errata/RHSA-2026:14874
- https://access.redhat.com/errata/RHSA-2026:19375
- https://access.redhat.com/errata/RHSA-2026:21017
- https://access.redhat.com/errata/RHSA-2026:22465
- https://access.redhat.com/errata/RHSA-2026:24853
- https://access.redhat.com/errata/RHSA-2026:48085
- https://access.redhat.com/errata/RHSA-2026:48758
- https://access.redhat.com/errata/RHSA-2026:59153
- https://access.redhat.com/errata/RHSA-2026:7224
- https://access.redhat.com/errata/RHSA-2026:8437
- https://access.redhat.com/security/cve/CVE-2026-27459
- https://bugzilla.redhat.com/show_bug.cgi?id=2448503
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.