# CVE-2023-20215: Security feature bypass in Cisco Secure Web Appliance

> Unauthenticated attackers can bypass web filtering rules on Cisco Secure Web Appliances by exploiting improper detection of encoded malicious traffic.

- **Severity:** Medium 5.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Aug 2023
- **Updated:** 2 Aug 2024
- **Also known as:** GHSA-4qcp-whvm-5mwc

## What is CVE-2023-20215?

CVE-2023-20215 is a medium-severity vulnerability in Cisco Asyncos, published on 3 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the scanning engines of Cisco AsyncOS Software for Cisco Secure Web Appliance could allow an unauthenticated, remote attacker to bypass a configured rule, allowing traffic onto a network that should have been blocked.

 This vulnerability is due to improper detection of malicious traffic when the traffic is encoded with a specific content format. An attacker could exploit this vulnerability by using an affected device to connect to a malicious server and receiving crafted HTTP responses. A successful exploit could allow the attacker to bypass an explicit block rule and receive traffic that should have been rejected by the device.

Weakness: CWE-202 (Exposure of Sensitive Information Through Data Queries)

## Which versions are affected by CVE-2023-20215?

It affects 1 product.


Products: Cisco Asyncos.

## How do I fix CVE-2023-20215?

No fix has been published for CVE-2023-20215 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-20215 being exploited?

There is no known exploitation of CVE-2023-20215 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Asyncos

- [CVE-2025-20393](https://insights.sbomify.com/CVE-2025-20393/): Cisco Multiple Products Improper Input Validation (critical 10.0, exploited in the wild)
- [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)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-20215 and fix it if it is affected.

What it is: CVE-2023-20215 is a medium-severity vulnerability in Cisco Asyncos, published on 3 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-20215 in the wild and no public exploit code.

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-2023-20215/ (Markdown: https://insights.sbomify.com/CVE-2023-20215/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-20215
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-20215
- OSV: https://osv.dev/vulnerability/CVE-2023-20215

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-20215/
Summaries are generated and may contain mistakes; the official description above is the record.