Use-after-free in Exim - CVE-2026-45185
Published: May 13, 2026
Vulnerability identifier: #VU131337
CSH Severity: Critical
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Red
CVE-ID: CVE-2026-45185
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Exim
Affected software:
Exim
Exim
Detailed vulnerability description
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to use-after-free in Exim's GnuTLS backend when handling BDAT message body transfers after a TLS close_notify alert is received before the transfer is complete. A remote attacker can send a TLS close_notify alert and then a final byte in cleartext on the same TCP connection to execute arbitrary code.
Only builds configured with USE_GNUTLS=yes are vulnerable, and exploitation requires use of the CHUNKING (BDAT) SMTP extension.
How to mitigate CVE-2026-45185
Install security update from vendor's website.