CVE-2026-45185
CVE-2026-45185
In short
Exim mail server has a use-after-free vulnerability in how it handles chunked email uploads over TLS. When an attacker sends a specially crafted TLS disconnect signal followed by extra data, it corrupts the server's memory and could allow remote code execution without authentication.
Technical detail
CVE-2026-45185 is a use-after-free (CWE-416) in Exim <4.99.3 when using GnuTLS, triggered during BDAT body parsing by sending a TLS close_notify mid-transfer followed by cleartext bytes on the same TCP connection. An unauthenticated remote attacker can achieve heap corruption and arbitrary code execution with a CVSS score of 9.8.
Summary generated and translated by AI from the official description.
Exim before 4.99.3, in certain GnuTLS configurations, has a remotely reachable use-after-free in the BDAT body parsing path. It is triggered when a client sends a TLS close_notify mid-body during a CHUNKING transfer, followed by a final cleartext byte on the same TCP connection. This can lead to heap corruption. An unauthenticated network attacker exploiting this vulnerability could execute arbitrary code.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected products
Exim · Eximpublic PoCs found — 3
githubgithub.com/liamromanis101/Dead.Letter-CVE-2026-45185★ 1githubgithub.com/MJ-bin/POC_CVE-2026-45185★ 1githubgithub.com/materaj2/cve-2026-45185-detection-script★ 0⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
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https://code.exim.org/exim/wiki/wiki/EximSecurityhttps://exim.orghttps://exim.org/static/doc/security/CVE-2026-45185.txthttps://exim.org/static/doc/security/EXIM-Security-2026-05-01.1/https://news.ycombinator.com/item?id=48111748https://www.openwall.com/lists/oss-security/2026/05/12/4https://xbow.com/blog/dead-letter-cve-2026-45185-xbow-found-rce-eximhttp://www.openwall.com/lists/oss-security/2026/05/12/25