A critical use-after-free vulnerability (CVE-2026-45185, CVSS 9.8) in the Exim mail transfer agent allows unauthenticated remote attackers to trigger heap corruption and execute arbitrary code via the BDAT body parsing path when using specific GnuTLS backend configurations. The vulnerability affects Exim versions prior to 4.99.3, and the developers have released updates to remediate the issue.
Beveiligingsadviezen Download Beveilingsadvies; NCSC-2026-0163 [1.0.0] Beveiligingsadvies NCSC-2026-0163 [1.0.0] Publicatie 15-05-2026 14:08 (Europe/Amsterdam) Prioriteit Normaal Betreft Kwetsbaarheid verholpen in Exim Kenmerken Use After Free Omschrijving De ontwikkelaars van Exim hebben een kwetsbaarheid verholpen in Exim mail transfer agent versies voorafgaand aan 4.99.3. De kwetsbaarheid betreft een use-after-free in het BDAT body parsing pad van Exim, specifiek bij gebruik van bepaalde GnuTLS backend configuraties. Een niet-geauthenticeerde aanvaller kan deze kwetsbaarheid op afstand misbruiken, wat leidt tot heap corruptie. De corrupte heap kan worden gebruikt om willekeurige code uit te voeren op het getroffen systeem. Oplossingen Exim heeft updates uitgebracht om de kwetsbaarheid te verhelpen. Zie bijgevoegde referenties voor meer informatie. Referenties http://www.openwall.com/lists/oss-security/2026/05/12/25 https://code.exim.org/exim/wiki/wiki/EximSecurity https://exim.org/static/doc/security/CVE-2026-45185.txt https://exim.org/static/doc/security/EXIM-Security-2026-05-01.1/EXIM-Security-2026-05-01.1.txt CVE's CVE-2026-45185 - CVSS (v3) 9.8 Producten Exim Exim Open Source Exim Disclaimer The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this page to enhance access to its information and security advisories. The use of this security advisory is subject to the following terms and conditions: NCSC-NL makes every reasonable effort to ensure that the content of this page is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or continuous keeping up-to-date. The information contained in this security advisory is intended solely for the purpose of providing general information to professional users. No rights can be derived from the information provided therein. NCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of this security advisory. This includes damage resulting from the inaccuracy of incompleteness of the information contained in the advisory. This security advisory is subject to Dutch law. All disputes related to or arising from the use of this advisory will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings.