Affected: Exim

Exim before 4.100.1, when Proxy-Protocol is used with an attacker-controlled proxy, allows attackers to read certain uninitialized data from stack memory.

Affected: Ubuntu:22.04:LTS: exim4, Ubuntu:24.04:LTS: exim4, Ubuntu:26.04:LTS: exim4

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)