Exim vulnerabilities

Summary

Timo Longin discovered that Exim incorrectly handled certain SMTP messages in PIPELINING/CHUNKING configurations. A remote attacker could possibly use this issue to perform SMTP smuggling. This issue only affected Ubuntu 14.04 LTS. (CVE-2023-51766) It was discovered that Exim incorrectly handled certain malformed JSON data in headers. A remote attacker could possibly use this issue to crash Exim, resulting in a denial of service, or execute arbitrary code. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-40685) It was discovered that Exim incorrectly handled certain malformed UTF-8 headers. A remote attacker could possibly use this issue to obtain sensitive information. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-40686) It was discovered that Exim incorrectly handled certain SPA resources. A remote attacker could possibly use this issue to crash Exim, resulting in a denial of service, or obtain sensitive information. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-40687) It was discovered that Exim incorrectly handled certain CHUNKING transfers in some GnuTLS configurations. A remote attacker could possibly use this issue to crash Exim, resulting in a denial of service, or execute arbitrary code. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-45185) Warisjeet Singh discovered that Exim incorrectly handled certain proxy connections in builds with proxy su Affected Ubuntu releases: 20.04, 18.04, 16.04, 14.04. CVEs: CVE-2026-40687, CVE-2026-45185, CVE-2026-40685, CVE-2026-40686, CVE-2023-51766, CVE-2026-48840.