USN-8834-1 release notes and known issues

Summary

It was discovered that Exim had an out-of-bounds write when Proxy-Protocol was used with an attacker-controlled proxy. A remote attacker could possibly use this issue to execute arbitrary code. (CVE-2026-94054) It was discovered that Exim had a use-after-free when certain non-default TLS settings were used with GnuTLS. A remote attacker could possibly use this issue to cause Exim to crash, resulting in a denial of service. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-94055) It was discovered that Exim allowed attackers to read uninitialized data from stack memory when Proxy-Protocol was used with an attacker-controlled proxy. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-94056) It was discovered that Exim allowed SMTP smuggling via crafted data sent after a rejection during DATA processing. A remote attacker could possibly use this issue to inject arbitrary email messages. (CVE-2026-94057)

Improvements and security content

• It was discovered that Exim had an out-of-bounds write when Proxy-Protocol was used with an attacker-controlled proxy. A remote attacker could possibly use this issue to execute arbitrary code. (CVE-2026-94054) It was discovered that Exim had a use-after-free when certain non-default TLS settings were used with GnuTLS. A remote attacker could possibly use this issue to cause Exim to crash, resulting in a denial of service. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-94055) It was discovered that Exim allowed attackers to read uninitialized data from stack memory when Proxy-Protocol was used with an attacker-controlled proxy. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-94056) It was discovered that Exim allowed SMTP smuggling via crafted data sent after a rejection during DATA processing. A remote attacker could possibly use this issue to inject arbitrary email messages. (CVE-2026-94057)

Affected products and versions

Recommended action

Review the official publisher document before deployment.

Lifecycle connections

These links connect the publisher update to related Lifecycle records without treating the update publication date as an end-of-support date.

Official publisher evidence