USN-8776-1: python-cryptography vulnerabilities

It was discovered that python-cryptography incorrectly accepted objects with immutable buffers when performing certain cipher operations. This would result in corrupted output, contrary to expectations. This issue only affected Ubuntu 18.04 LTS. (CVE-2023-23931)

It was discovered that python-cryptography reported the outcome of decrypting PKCS#7 enveloped data in distinguishable ways, and with observable timing differences. A remote attacker could possibly use this issue to recover the key used to encrypt the message contents, and obtain sensitive information. This issue only affected Ubuntu 26.04 LTS.

(CVE-2026-69247) Jack Lloyd discovered that python-cryptography incorrectly handled wildcard DNS names when enforcing the name constraints of a certificate authority. A remote attacker could possibly use this issue to have an invalid certificate chain accepted, and use names outside of the permitted ones. This issue only affected Ubuntu 26.04 LTS.

(CVE-2026-69248) Samuel Judson discovered that python-cryptography incorrectly handled certificate chains that contained duplicate certificates. A remote attacker could possibly use this issue to cause python-cryptography to use excessive resources, leading to a denial of service. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-69249)