Ubuntu Security Notice 4994-1 - Marc Stern discovered that the Apache mod_proxy_http module incorrectly handled certain requests. A remote attacker could possibly use this issue to cause Apache to crash, resulting in a denial of service. This issue only affected Ubuntu 20.04 LTS, Ubuntu 20.10, and Ubuntu 21.04. Antonio Morales discovered that the Apache mod_auth_digest module incorrectly handled certain Digest nonces. A remote attacker could possibly use this issue to cause Apache to crash, resulting in a denial of service. Various other issues were also addressed.
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Ubuntu Security Notice 4993-1 - Kirin discovered that Dovecot incorrectly escaped kid and azp fields in JWT tokens. A local attacker could possibly use this issue to validate tokens using arbitrary keys. This issue only affected Ubuntu 20.10 and Ubuntu 21.04. Fabian Ising and Damian Poddebniak discovered that Dovecot incorrectly handled STARTTLS when using the SMTP submission service. A remote attacker could possibly use this issue to inject plaintext commands before STARTTLS negotiation. Various other issues were also addressed.
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