==========================================================================
Ubuntu Security Notice USN-8115-1
March 23, 2026

pyopenssl vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS

Summary:

Several security issues were fixed in pyOpenSSL.

Software Description:
- pyopenssl: Python wrapper around the OpenSSL library

Details:

It was discovered that pyOpenSSL incorrectly handled exceptions in the
tlsext_servername callback. This could result in connections being
accepted after an exception, contrary to expectations. (CVE-2026-27448)

It was discovered that pyOpenSSL incorrectly handled the DTLS cookie
generation callback. If a callback provided cookie values greater than 256
bytes, an attacker could use this issue to cause pyOpenSSL to crash,
resulting in a denial of service, or possibly execute arbitrary code. This
issue only affected Ubuntu 24.04 LTS and Ubuntu 25.10. (CVE-2026-27459)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 25.10
  python3-openssl                 25.0.0-1ubuntu0.1

Ubuntu 24.04 LTS
  python3-openssl                 23.2.0-1ubuntu0.1

Ubuntu 22.04 LTS
  python3-openssl                 21.0.0-1ubuntu0.1

In general, a standard system update will make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-8115-1
  CVE-2026-27448, CVE-2026-27459

Package Information:
  https://launchpad.net/ubuntu/+source/pyopenssl/25.0.0-1ubuntu0.1
  https://launchpad.net/ubuntu/+source/pyopenssl/23.2.0-1ubuntu0.1
  https://launchpad.net/ubuntu/+source/pyopenssl/21.0.0-1ubuntu0.1