# CVE-2025-20393: Cisco Multiple Products Improper Input Validation

> Unauthenticated remote attackers can execute arbitrary system commands with root privileges via crafted HTTP requests to the Spam Quarantine feature.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 17 Dec 2025 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 17 Dec 2025
- **Updated:** 7 Oct 2026
- **Also known as:** GHSA-mrgj-cg36-fgq8

## What is CVE-2025-20393?

CVE-2025-20393 is a critical command injection vulnerability in Cisco Asyncos, published on 17 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2025-20393?

It affects 1 product.


Products: Cisco Asyncos.

## How do I fix CVE-2025-20393?

No fix has been published for CVE-2025-20393 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 24 Dec 2025.

## Is CVE-2025-20393 being exploited?

Yes. Attackers have exploited CVE-2025-20393 in the wild since at least 17 Dec 2025.

Public exploit code:

- Cisco is aware of a potential vulnerability.  Cisco is currently investigating and will update these details as appropriate as more information becomes available. (github_poc): https://github.com/cyberleelawat/CVE-2025-20393
- https://github.com/KingHacker353/CVE-2025-20393 (github_poc): https://github.com/KingHacker353/CVE-2025-20393
- CVE-2025-20393 (github_poc): https://github.com/redpack-kr/Blackash-CVE-2025-20393
- This tool helps identify exposure to CVE-2025-20393 by checking for open TCP/6025 ports, responsive Spam Quarantine interfaces, and known post-exploitation IOCs. (github_poc): https://github.com/cyberdudebivash/CYBERDUDEBIVASH-Cisco-AsyncOS-CVE-2025-20393-Scanner

## Other vulnerabilities in Cisco Asyncos

- [CVE-2026-76519](https://insights.sbomify.com/CVE-2026-76519/): Cisco Secure Email Gateway Relative Path Traversal (critical 9.8, exploited in the wild)
- [CVE-2026-76461](https://insights.sbomify.com/CVE-2026-76461/): Cisco Secure Email Gateway SQL Injection (critical 9.8, exploited in the wild)
- [CVE-2024-20435](https://insights.sbomify.com/CVE-2024-20435/): Command injection in Cisco Secure Web Appliance (high 8.8)
- [CVE-2019-15956](https://insights.sbomify.com/CVE-2019-15956/): Cisco Web Security Appliance Unauthorized Device Reset Vulnerability (high 8.8)
- [CVE-2021-34698](https://insights.sbomify.com/CVE-2021-34698/): Cisco Web Security Appliance Proxy Service Denial of Service Vulnerability (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-20393 and fix it if it is affected.

What it is: CVE-2025-20393 is a critical command injection vulnerability in Cisco Asyncos, published on 17 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2025-20393 in the wild since at least 17 Dec 2025.

Affected product: Cisco Asyncos. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-20393/ (Markdown: https://insights.sbomify.com/CVE-2025-20393/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-20393
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-20393
- OSV: https://osv.dev/vulnerability/CVE-2025-20393

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-20393/
Summaries are generated and may contain mistakes; the official description above is the record.