Raw vector
CVSS:3.1/AV:N/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-2024-20401 is a critical-severity Absolute Path Traversal (CWE-36) vulnerability in Cisco Secure Email Gateway. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Junk Data (T1001.001); ranked in the top 17% of CVEs by exploit likelihood; 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.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
A vulnerability in the content scanning and message filtering features of Cisco Secure Email Gateway allows an unauthenticated remote attacker to overwrite arbitrary files on the underlying operating system. The issue stems from improper handling of email attachments when file analysis and content filters are enabled, and it is tracked under CWE-36 with a CVSS 3.1 score of 9.8.
An attacker can exploit the flaw simply by sending a crafted email attachment through an affected device. Successful exploitation permits replacement of any file on the file system, enabling actions such as adding root-privileged users, altering device configuration, executing arbitrary code, or inducing a permanent denial-of-service condition that requires manual recovery via Cisco TAC.
The Cisco Security Advisory cisco-sa-esa-afw-bGG2UsjH details mitigation steps and is available at the vendor's security center.
EPSS for this CVE rose from lower values to a peak of 0.1391 before receding to the current score of 0.0766, indicating a period of increased exploitation interest after disclosure.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2024-18116
Vulnerability Data
A vulnerability in the content scanning and message filtering features of Cisco Secure Email Gateway could allow an unauthenticated, remote attacker to overwrite arbitrary files on the underlying operating system. This vulnerability is due to improper handling of email attachments…
more
when file analysis and content filters are enabled. An attacker could exploit this vulnerability by sending an email that contains a crafted attachment through an affected device. A successful exploit could allow the attacker to replace any file on the underlying file system. The attacker could then perform any of the following actions: add users with root privileges, modify the device configuration, execute arbitrary code, or cause a permanent denial of service (DoS) condition on the affected device. Note: Manual intervention is required to recover from the DoS condition. Customers are advised to contact the Cisco Technical Assistance Center (TAC) to help recover a device in this condition.
- 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 stops construction of absolute paths from untrusted data before they reach file operations.
Enforced access authorizations can limit which resources are reachable even if a 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 absolute path 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.8.25 mandates secure SDLC practices (secure requirements, checkpoints, secure coding guidelines, testing including code scans/penetration tests) that reach many path-traversal instances in custom software, but leaves a bounded remainder (e.g. third-party components, misconfigured outsourced development, or incomplete enforcement of guidelines) where the weakness can still be introduced and exploited.
Application security requirements typically mandate controls against path traversal in file-access functions.
A.8.27 mandates security-by-design principles (least privilege, default-deny, distrust-external-input, hardening, design review against attack patterns) that reach a minority slice of absolute path traversal (e.g. explicit path canonicalization rules or sandboxing), but most instances arise from ordinary string-concatenation flaws in custom code that the clause's high-level engineering principles do not themselves stop from being written or exploited.
Secure coding standards directly require neutralization of absolute path sequences in pathname construction.
Security testing in development can detect absolute path traversal via static analysis and fuzzing.