CVE-2026-66140
Exim ≤ 4.99.5
Raw vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-66140 is a high-severity Path Traversal: '../filedir' (CWE-24) vulnerability in Exim Exim. Its CVSS base score is 8.4 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked at the 17th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-48478
Vulnerability Data
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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Input validation directly neutralizes '../' sequences in externally-supplied pathnames before they are resolved.
Enforced access authorizations can limit the damage even when path traversal succeeds.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require input validation and path sanitization that prevent ../ traversal.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Secure SDLC mandates input validation and path canonicalization that directly block ../ traversal.
Application security requirements explicitly call for controls against path traversal in file-handling functions.
Secure architecture principles reduce attack surface but do not prescribe the specific coding fix.
Secure coding standards require neutralizing ../ sequences and canonicalizing paths before file operations.
Security testing in development catches path-traversal flaws before release.
Information access restriction limits which files can be reached, mitigating impact of traversal.