Cyber Resilience

CVE-2026-66140

Exim ≤ 4.99.5

Published
24 July 2026
Modified
17 August 2026
CVSS Score v3.1 8.4
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0027 20th percentile
Risk Priority 60 floored blend · peak EPSS

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 20th 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

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)
CWE-24

Related Threats

MITRE ATT&CK Enterprise Techniques

T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-0416Shared CWE-24
CVE-2025-51661Shared CWE-24
CVE-2026-49103Shared CWE-24
CVE-2023-7040Shared CWE-24
CVE-2023-53691Shared CWE-24
CVE-2026-22810Shared CWE-24
CVE-2023-3057Shared CWE-24
CVE-2026-44942Shared CWE-24
CVE-2025-32807Shared CWE-24
CVE-2026-40318Shared CWE-24

Affected Assets

exim
exim
≤ 4.99.5

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match

Input validation directly neutralizes '../' sequences in externally-supplied pathnames before they are resolved.

AC-3 Access Enforcement partial match

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.

PR.PS-06 mostly match
prevents

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.

A.8.28 Secure coding mostly match
prevents

Secure coding standards require neutralizing ../ sequences and canonicalizing paths before file operations.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development catches path-traversal flaws before release.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates input validation and path canonicalization that directly block ../ traversal.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly call for controls against path traversal in file-handling functions.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles reduce attack surface but do not prescribe the specific coding fix.

A.8.3 Information access restriction partial match
mitigates

Information access restriction limits which files can be reached, mitigating impact of traversal.

References