Critical and high severity Exim vulnerabilities: everything you need to know

Multiple critical and high-severity vulnerabilities in the Exim Mail Transfer Agent—particularly CVE-2023-42115 (CVSS 9.8)—can allow unauthenticated remote code execution when specific features (such as EXTERNAL authentication, SPA/NTLM, certain ACL SPF conditions, or untrusted proxy/DNS setups) are enabled; vendors have issued patches for some CVEs (Exim 4.96.1 / 4.97) and provided workarounds (disable affected features or restrict access), but several issues remain unpatched and exploitation in the wild is expected.