How severe is CVE-2026-66140?

CVE-2026-66140 has a CVSS 3.x base score of 8.4, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-66140 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-66140?

CVE-2026-66140 affects Exim. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-66140?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-66140 published?

CVE-2026-66140 was published on 2026-07-24 and last updated on 2026-08-17.

CVE-2026-66140

CVE-2026-66140 is a high-severity vulnerability in Exim with a CVSS 3.x base score of 8.4. 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-24.

Key facts

Severity: High (CVSS 3.x base score 8.4)
EPSS exploit prediction: 0% (17th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-24
Affected product: Exim
Published: 2026-07-24
Last modified: 2026-08-17

Description

Exim before 4.99.5 allows directory traversal to access files outside of the spool area, and consequently gain privileges, because arguments related to queue-name are mishandled.

Frequently asked questions

What is CVE-2026-66140?: Exim before 4.99.5 allows directory traversal to access files outside of the spool area, and consequently gain privileges, because arguments related to queue-name are mishandled.
How severe is CVE-2026-66140?: CVE-2026-66140 has a CVSS 3.x base score of 8.4, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-66140 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-66140?: CVE-2026-66140 affects Exim. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-66140?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-66140 published?: CVE-2026-66140 was published on 2026-07-24 and last updated on 2026-08-17.

References

https://openwall.com/lists/oss-security/2026/07/22/9

Affected products (1)

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

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Threat intelligence

Threat-intel indicators referencing this CVE:

207.244.224.200 (ipv4-addr)
103.159.85.90 (ipv4-addr)
51.75.21.168 (ipv4-addr)
147.182.228.12 (ipv4-addr)
162.240.228.207 (ipv4-addr)