How severe is CVE-2026-40687?

CVE-2026-40687 has a CVSS 3.x base score of 4.8, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability low.

Is CVE-2026-40687 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-40687?

CVE-2026-40687 affects Exim. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-40687?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-40687 have an EU (EUVD) identifier?

Yes. CVE-2026-40687 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-26445.

When was CVE-2026-40687 published?

CVE-2026-40687 was published on 2026-04-30 and last updated on 2026-06-17.

CVE-2026-40687

CVE-2026-40687 is a medium-severity vulnerability in Exim with a CVSS 3.x base score of 4.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-909.

Key facts

Severity: Medium (CVSS 3.x base score 4.8)
EPSS exploit prediction: 0% (29th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-26445
Weakness: CWE-909
Affected product: Exim
Published: 2026-04-30
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-40687?: 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.
How severe is CVE-2026-40687?: CVE-2026-40687 has a CVSS 3.x base score of 4.8, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability low.
Is CVE-2026-40687 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-40687?: CVE-2026-40687 affects Exim. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-40687?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-40687 have an EU (EUVD) identifier?: Yes. CVE-2026-40687 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-26445.
When was CVE-2026-40687 published?: CVE-2026-40687 was published on 2026-04-30 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*

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Other CWE-909 vulnerabilities

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CVE-2021-23994 — High (CVSS 8.8): A WebGL framebuffer was not initialized early enough, resulting in memory corruption and an out of bound write. This…
CVE-2020-11741 — High (CVSS 8.8): An issue was discovered in xenoprof in Xen through 4.13.x, allowing guest OS users (with active profiling) to obtain…
CVE-2024-9780 — High (CVSS 7.8): ITS dissector crash in Wireshark 4.4.0 allows denial of service via packet injection or crafted capture file

Browse all CWE-909 vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

193.202.11.112 (ipv4-addr)
76.12.128.249 (ipv4-addr)
50.116.72.139 (ipv4-addr)
166.62.41.190 (ipv4-addr)
160.187.147.124 (ipv4-addr)
132.148.155.138 (ipv4-addr)
77.221.151.241 (ipv4-addr)
37.221.254.200 (ipv4-addr)