oss-security - pyOpenSSL 26.0.0 released with two CVE fixes

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Message-ID: <6db25e1f-792b-4655-871b-82812dc0fd6f@oracle.com>
Date: Fri, 20 Mar 2026 16:11:32 -0700
From: Alan Coopersmith <alan.coopersmith@...cle.com>
To: oss-security@...ts.openwall.com
Subject: pyOpenSSL 26.0.0 released with two CVE fixes

https://www.pyopenssl.org/en/latest/changelog.html lists among the changes
in pyOpenSSL 26.0.0:

> * Properly raise an error if a DTLS cookie callback returned a cookie longer
>   than DTLS1_COOKIE_LENGTH bytes. Previously this would result in a
>   buffer-overflow. Credit to dark_haxor for reporting the issue.
>   CVE-2026-27459
> 
> * Context.set_tlsext_servername_callback now handles exceptions raised in
>   the callback by calling sys.excepthook and returning a fatal TLS alert.
>   Previously, exceptions were silently swallowed and the handshake would
>   proceed as if the callback had succeeded.
>   Credit to Leury Castillo for reporting this issue.
>   CVE-2026-27448

These are also listed at:

https://github.com/pyca/pyopenssl/security/advisories/GHSA-5pwr-322w-8jr4
https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424

but with not much more detail provided.

-- 
         -Alan Coopersmith-                 alan.coopersmith@...cle.com
          Oracle Solaris Engineering - https://blogs.oracle.com/solaris

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