CVE-2026-45185: Exim remote code execution (CVSS 9.8)

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.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Affected products

Exim≥ 4.97 < 4.99.3

Remediation

Fixed in

Exim≥ 4.99.3

Patch & vendor advisories

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

References

https://code.exim.org/exim/wiki/wiki/EximSecurityVendor Advisory
https://exim.orgProduct
https://exim.org/static/doc/security/CVE-2026-45185.txtBroken Link
https://exim.org/static/doc/security/EXIM-Security-2026-05-01.1/Release Notes
https://news.ycombinator.com/item?id=48111748Issue Tracking
https://www.openwall.com/lists/oss-security/2026/05/12/4Mailing ListThird Party Advisory
https://xbow.com/blog/dead-letter-cve-2026-45185-xbow-found-rce-eximThird Party Advisory
http://www.openwall.com/lists/oss-security/2026/05/12/25Mailing ListThird Party Advisory

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-45185 being actively exploited?

CVE-2026-45185 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.94%.

How severe is CVE-2026-45185?

CVE-2026-45185 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.94% probability of exploitation.

Which products are affected by CVE-2026-45185?

Affected products include Exim.

How do I fix CVE-2026-45185?

Upgrade affected software to a fixed version, for example Exim 4.99.3 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-45185 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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