[EXIM-Security-2026-05-01.1] Security

Heiko Schlittermann via Exim-users <[email protected]> Tue, 12 May 2026 16:16:21 +0200

Newsgroups	gmane.mail.exim.user
Organization	schlittermann -- internet & unix support
Message-ID	<[email protected]>

Hello,

The Exim maintainers are releasing an important security update to address a critical vulnerability affecting certain Exim configurations.

Vulnerability Details

A remotely reachable Use-After-Free (UAF) vulnerability has been identified in Exim's BDAT (binary data transmission) body parsing path when using the GnuTLS backend. This vulnerability can lead to heap corruption and potential code execution.

Affected Versions and Configurations

This vulnerability affects Exim versions 4.97 through 4.99.x that:
- Are built with GnuTLS support
- Have STARTTLS and CHUNKING advertised

Recommended Action

We strongly recommend all affected users upgrade to Exim 4.99.3 or later immediately.

Obtaining the Fix

Fixed versions are available:
- Repository: https://code.exim.org/exim/exim (branch: exim-4.99+fixes, tag: exim-4.99.3) (signed by me)
- Tarballs: https://downloads.exim.org/exim4/ (signed by me)
- Please see the Exim website for detailed upgrade instructions

Additional Information

- Distros already have coordinated access to patches
- Internal tracking ID: EXIM-Security-2026-05-01.1
- Full technical details will be available: https://exim.org/static/doc/security/EXIM-Security-2026-05-01.1/

Thank you for your cooperation.
And special thanks to the reporter at xbow security.

    Best regards from Dresden/Germany
    Viele Grüße aus Dresden
    Heiko Schlittermann
-- 
 SCHLITTERMANN.de ---------------------------- internet & unix support -
 Heiko Schlittermann, Dipl.-Ing. (TU)              fon +49.351.8029981 -
 gnupg encrypted messages are welcome --------------- key ID: F69376CE -



----- End forwarded message -----


-- 
## subscription configuration (requires account):
##   https://lists.exim.org/mailman3/postorius/lists/exim-users.lists.exim.org/
## unsubscribe (doesn't require an account):
##   [email protected]
## Exim details at https://www.exim.org/
## Please use the Wiki with this list - https://code.exim.org/exim/wiki/wiki

signature.asc (application/pgp-signature, 833 B)