CVE-2025-20393: Cisco Multiple Products Improper Input Validation Vulnerability
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
A vulnerability in the Spam Quarantine feature of Cisco AsyncOS Software for Cisco Secure Email Gateway and Cisco Secure Email and Web Manager could allow an unauthenticated, remote attacker to execute arbitrary system commands on an affected device with root privileges. This vulnerability is due to insufficient validation of HTTP requests by the Spam Quarantine feature. An attacker could exploit this vulnerability by sending a crafted HTTP request to the affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying operating system with root privileges.
Description quoted from the CVE record (assigned by cisco, published 2025-12-17).
Weakness: Improper Input Validation
How it can be exploited
Exploitable over the network with low attack complexity needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.
- On CISA KEV since
- 2025-12-17
- US federal deadline
- 2025-12-24
- Ransomware use
- Not known
Public exploit evidence (Exploit Observer)
Also known as: BDU:2025-16120, CNNVD-202512-3279, EUVD-2025-203911, GHSA-mrgj-cg36-fgq8
VEDAS cluster: VEDAS:GATORESCAPE
Exploit Observer links 7 pieces of public exploit code or detection modules that name this CVE or one of its aliases.
Exploit code and modules (7)
Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.
- Code repository: https://github.com/ashwesker/ashwesker-cve-2025-20393
- Code repository: https://github.com/b1gchoi/cve-2025-20393
- Code repository: https://github.com/cyberdudebivash/cyberdudebivash-cisco-asyncos-cve-2025-20393-scanner
- Code repository: https://github.com/cyberleelawat/cve-2025-20393
- Code repository: https://github.com/kinghacker353/cve-2025-20393
- Code repository: https://github.com/redpack-kr/blackash-cve-2025-20393
- Code repository: https://github.com/thesystemowner/cve-2025-20393-poc
Research and write-ups (2)
- Research or write-up: https://socprime.com/blog/cve-2025-20393-vulnerability-exploitation
- Research or write-up: https://starlabs.sg/blog/2026/01-pickling-the-mailbox-a-deep-dive-into-cve-2025-20393
Vulnerability databases and vendor advisories (6)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2025-203911
- Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-mrgj-cg36-fgq8
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2025-20393
- Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-20393
- Vulnerability database or vendor advisory: https://www.cnnvd.org.cn/home/globalSearch?keyword=CNNVD-202512-3279
- Vulnerability database or vendor advisory: https://www.secpod.com/blog/zero-day-crisis-cve-2025-20393-unpatched-on-cisco-email-gateways-exploited-by-china-linked-hackers
114 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.324
likely to be attacked soon - VEDAS
- 0.972
strong exploit evidence - On CISA KEV
- Yes, since 2025-12-17
- Detection rule
- None yet
Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| Cisco Cisco Secure Email | version 14.0.0-698 version 13.5.1-277 version 13.0.0-392 version 14.2.0-620 version 13.0.5-007 version 13.5.4-038 version 14.2.1-020 version 14.3.0-032 and 10 more ranges | Not stated |
| Cisco Cisco Secure Email and Web Manager | version 13.6.2-023 version 13.6.2-078 version 13.0.0-249 version 13.0.0-277 version 13.8.1-052 version 13.8.1-068 version 13.8.1-074 version 14.0.0-404 and 18 more ranges | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
Exploit Observer also maps it to: cisco asyncos, cisco_systems,_inc. cisco_secure_email_and_web_manager, cisco_systems,_inc. cisco_secure_email_gateway.
How to fix it
CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Vendor guidance:
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-attack-N9bf4
- https://nvd.nist.gov/vuln/detail/CVE-2025-20393
How to detect it
There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.
References
Government sources
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-20393 (government-resource)
Other references
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.