Exim 4.99.2 fixes 4 CVEs

[Solar Designer <solar () openwall com>]

Bernard helpfully notified distros of this upcoming security release on
April 24 and then of the release itself on April 29, but unfortunately
did not bring this to oss-security as expected - so I am doing it now,
delayed by one day.

This was also sent to the public exim-announce list yesterday:

https://lists.exim.org/lurker/message/20260429.121733.f58d9686.en.html

but it isn't prominently visible on the Exim website now.  I tried
clicking the Security link in the navigation on top, but this merely
opened a directory listing with some text files and subdirectories in
there, with all file timestamps showing as 30-Apr-2026 10:29 and so
nothing clearly standing out as new.  Looks like something to improve.

----- Forwarded message from Bernard Quatermass <bernardq () exim org> -----

From: Bernard Quatermass <bernardq () exim org>
To: "Distros @ oss-security openwall" <distros () vs openwall org>
Subject: Re: [vs-plain] EXIM-Security-2026-04-24
CC: "security () exim org" <security () exim org>
Date: Wed, 29 Apr 2026 13:19:42 +0100

we are pleased to announce the availability of release 4.99.2 of Exim.

This is a security release.

It fixes the following vulnerabilities.

CVE-2026-40684     Possible crash with malicious DNS data when using musl libc

   On systems using musl libc (not glibc) due to an oddity in octal printing
   it is possible to crash the connection instance when malformed DNS data
   is present in PTR records.

CVE-2026-40685     Possible OOB read/write on corrupt JSON in header

   configurations using json operators on invalid externally-provided input
   could trigger heap corruption.

CVE-2026-40686     Possible OOB read with large UTF8 trailing characters

   configurations using utf8 operators on malformed utf8 in headers could
   trigger OOB reads and might trigger some data leak if error
   messages are required for subsequent emails in the current connection
   and similar malformed headers are present.

CVE-2026-40687     Possible OOB read/write with SPA authenticator

   in configurations using the SPA authentication driver to a hostile/compromised
   external SPA/NTLM connnection it is possible to trigger an OOB read/write
   and crash the connection instance or possibly leak heap data to the instance.

Older Exim versions may or may not be vulnerable but are not actively maintained.


We would like to thank the thousands of unnamed and uncredited authors whose
works were ingested into the slopbots to "assist" in the reports for these vulnerabilities.



Exim 4.99.2 is available:

  * as tarball
    * https://ftp.exim.org/pub/exim/exim4/
    * https://code.exim.org/exim/exim/releases

  * directly from Git: https://code.exim.org/exim/exim
    tag: exim-4.99.2


The signatures on the release tarballs should be

  *  key ID 0xBCE58C8CE41F32DF
     Email: jgh () exim org



-- 
Bernard Quatermass

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