Is CVE-2026-40687 in the CISA KEV catalog?

No. CVE-2026-40687 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-40687?

CVE-2026-40687 has a CVSS v3 base score of 4.8 (MEDIUM).

What is the EPSS score for CVE-2026-40687?

CVE-2026-40687 has an EPSS score of 0.37% (29th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-40687?

Upgrade exim4 on debian 12 to 4.96-15+deb12u9 or later. Fixes are available for 7 affected products.

CVE & CISA-KEV Catalog

CVE-2026-40687

MEDIUM

4.8

CVSS v3

NVD

Description

In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that divulges data from uninitialized heap memory.

CWE-909

How to fix

Remediation Available

exim4Debian

Fixed in:4.96-15+deb12u9CVE-2026-40687

Fixed in:4.98.2-1+deb13u2CVE-2026-40687

Fixed in:4.99.2-1CVE-2026-40687

exim4Ubuntu

Fixed in:4.82-3ubuntu2.4+esm9USN-8382-1

Fixed in:4.86.2-2ubuntu2.6+esm9USN-8382-1

Fixed in:4.90.1-1ubuntu1.10+esm6USN-8382-1

Fixed in:4.93-13ubuntu1.12+esm1USN-8382-1

Fixed in:4.95-4ubuntu2.7USN-8228-1

Fixed in:4.97-4ubuntu4.4USN-8228-1

Fixed in:4.98.2-1ubuntu2.1USN-8228-1

exim4-baseUbuntu

Fixed in:4.82-3ubuntu2.4+esm9USN-8382-1

Fixed in:4.86.2-2ubuntu2.6+esm9USN-8382-1

Fixed in:4.90.1-1ubuntu1.10+esm6USN-8382-1

Fixed in:4.93-13ubuntu1.12+esm1USN-8382-1

Fixed in:4.95-4ubuntu2.7USN-8228-1

Fixed in:4.97-4ubuntu4.4USN-8228-1

Fixed in:4.98.2-1ubuntu2.1USN-8228-1

exim4-daemon-heavyUbuntu

Fixed in:4.82-3ubuntu2.4+esm9USN-8382-1

Fixed in:4.86.2-2ubuntu2.6+esm9USN-8382-1

Fixed in:4.90.1-1ubuntu1.10+esm6USN-8382-1

Fixed in:4.93-13ubuntu1.12+esm1USN-8382-1

exim4-daemon-lightUbuntu

Fixed in:4.82-3ubuntu2.4+esm9USN-8382-1

Fixed in:4.86.2-2ubuntu2.6+esm9USN-8382-1

Fixed in:4.90.1-1ubuntu1.10+esm6USN-8382-1

Fixed in:4.93-13ubuntu1.12+esm1USN-8382-1

exim4-devUbuntu

Fixed in:4.82-3ubuntu2.4+esm9USN-8382-1

Fixed in:4.86.2-2ubuntu2.6+esm9USN-8382-1

Fixed in:4.90.1-1ubuntu1.10+esm6USN-8382-1

Fixed in:4.93-13ubuntu1.12+esm1USN-8382-1

eximon4Ubuntu

Fixed in:4.82-3ubuntu2.4+esm9USN-8382-1

Fixed in:4.86.2-2ubuntu2.6+esm9USN-8382-1

Fixed in:4.90.1-1ubuntu1.10+esm6USN-8382-1

Fixed in:4.93-13ubuntu1.12+esm1USN-8382-1

Fixed in:4.95-4ubuntu2.7USN-8228-1

Fixed in:4.97-4ubuntu4.4USN-8228-1

Fixed in:4.98.2-1ubuntu2.1USN-8228-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityNone

AvailabilityLow

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

Exploit Intelligence

0.37%probability of exploitation in 30 days

29thpercentile

Low risk: more likely to be exploited than 29% of all known CVEs.

References

Patch1

code.exim.org

Vendor Advisory1

exim.org

Third-Party Advisory1

openwall.com

Other references1

exim.org

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-01.