CVE-2026-45185
Exim GnuTLS Use-After-Free Remote Code Execution Vulnerability
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.
INFO
Published Date :
May 12, 2026, 8:16 p.m.
Last Modified :
May 28, 2026, 6:46 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | [email protected] |
Solution
- Update Exim to version 4.99.3 or later.
- Verify GnuTLS configuration settings.
- Monitor network traffic for suspicious activity.
Public PoC/Exploit Available at Github
CVE-2026-45185 has a 2 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-45185.
| URL | Resource |
|---|---|
| https://code.exim.org/exim/wiki/wiki/EximSecurity | Vendor Advisory |
| https://exim.org | Product |
| https://exim.org/static/doc/security/CVE-2026-45185.txt | Broken Link |
| https://exim.org/static/doc/security/EXIM-Security-2026-05-01.1/ | Release Notes |
| https://news.ycombinator.com/item?id=48111748 | Issue Tracking |
| https://www.openwall.com/lists/oss-security/2026/05/12/4 | Mailing List Third Party Advisory |
| https://xbow.com/blog/dead-letter-cve-2026-45185-xbow-found-rce-exim | Third Party Advisory |
| http://www.openwall.com/lists/oss-security/2026/05/12/25 | Mailing List Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-45185 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-45185
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
POC_CVE-2026-45185 for nuclei-templates
Dockerfile
These detection scripts are property of the SECPlayground Platform. Two safe detection scripts. Neither drives the close_notify-mid-BDAT trigger, so they will not crash the daemon or leave panic-log entries. Both verdicts are "likely vulnerable" — distinguishing GnuTLS from OpenSSL builds remotely is not reliable without exploitation.
Lua
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-45185 vulnerability anywhere in the article.
-
security.nl
Kritiek Exim-lek maakt remote code execution op mailserver mogelijk
Een kritieke kwetsbaarheid in Exim maakt op mailservers remote code execution door een ongeauthenticeerde aanvaller mogelijk. Er is een update verschenen waarmee het probleem (CVE-2026-45185) wordt ve ... Read more
-
CybersecurityNews
New Critical Exim Mailer Allows Remote Attacker to Execute Arbitrary Code
A critical vulnerability in the widely used Exim mail server allows unauthenticated attackers to execute arbitrary code and fully compromise exposed servers. Federico Kirschbaum, head of the Security ... Read more
-
The Cyber Express
Exim BDAT Vulnerability Exposes Email Servers to Remote Attacks
A newly revealed Exim BDAT vulnerability is affecting some email server setups that use Exim as their Mail Transfer Agent (MTA), prompting security attention due to its severity. Tracked as CVE-2026-4 ... Read more
The following table lists the changes that have been made to the
CVE-2026-45185 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
May. 28, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:* versions from (including) 4.97 up to (excluding) 4.99.3 Added Reference Type CVE: http://www.openwall.com/lists/oss-security/2026/05/12/25 Types: Mailing List, Third Party Advisory Added Reference Type MITRE: https://code.exim.org/exim/wiki/wiki/EximSecurity Types: Vendor Advisory Added Reference Type MITRE: https://exim.org Types: Product Added Reference Type MITRE: https://exim.org/static/doc/security/CVE-2026-45185.txt Types: Broken Link Added Reference Type MITRE: https://exim.org/static/doc/security/EXIM-Security-2026-05-01.1/ Types: Release Notes Added Reference Type MITRE: https://news.ycombinator.com/item?id=48111748 Types: Issue Tracking Added Reference Type MITRE: https://www.openwall.com/lists/oss-security/2026/05/12/4 Types: Mailing List, Third Party Advisory Added Reference Type MITRE: https://xbow.com/blog/dead-letter-cve-2026-45185-xbow-found-rce-exim Types: Third Party Advisory -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
May. 13, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/05/12/25 -
CVE Modified by [email protected]
May. 12, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-416 -
New CVE Received by [email protected]
May. 12, 2026
Action Type Old Value New Value Added 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. Added Reference https://code.exim.org/exim/wiki/wiki/EximSecurity Added Reference https://exim.org Added Reference https://exim.org/static/doc/security/CVE-2026-45185.txt Added Reference https://exim.org/static/doc/security/EXIM-Security-2026-05-01.1/ Added Reference https://news.ycombinator.com/item?id=48111748 Added Reference https://www.openwall.com/lists/oss-security/2026/05/12/4 Added Reference https://xbow.com/blog/dead-letter-cve-2026-45185-xbow-found-rce-exim