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CVE-2026-45185

Published: May 12, 2026

Modified: May 14, 2026

PUBLISHED

CVSS v3.1

9.8

CRITICAL

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.

Vendor	Product	Versions
Exim	Exim	affected `4.97 - < 4.99.3`

Weaknesses (CWE)

CVSS v3.1 Details

CVSS v3.1 Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

References

https://exim.org

https://code.exim.org/exim/wiki/wiki/EximSecurity

https://exim.org/static/doc/security/CVE-2026-45185.txt

https://xbow.com/blog/dead-letter-cve-2026-45185-xbow-found-rce-exim

https://news.ycombinator.com/item?id=48111748

https://www.openwall.com/lists/oss-security/2026/05/12/4

https://exim.org/static/doc/security/EXIM-Security-2026-05-01.1/

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