# CVE-2019-15971: Cisco Email Security Appliance MP3 Content Filter Bypass Vulnerability

> An unauthenticated remote attacker can bypass email content filters by sending a crafted MP3 file, allowing malicious emails to pass through the Cisco Email Security Appliance.

- **Severity:** Medium 5.8 (`CVSS:3.0/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:** 26 Nov 2019
- **Updated:** 19 Nov 2024
- **Also known as:** GHSA-qrpg-pg76-xv44

## What is CVE-2019-15971?

CVE-2019-15971 is a medium-severity vulnerability in Cisco Email Security Appliance (ESA), published on 26 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the MP3 detection engine of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass configured content filters on the device. The vulnerability is due to improper validation of certain MP3 file types. An attacker could exploit this vulnerability by sending a crafted MP3 file through the targeted device. A successful exploit could allow the attacker to bypass configured content filters that would normally drop the email.

Weakness: CWE-345 (Insufficient Verification of Data Authenticity), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2019-15971?

It affects 1 product.


Products: Cisco Email Security Appliance Firmware.

## How do I fix CVE-2019-15971?

No fix has been published for CVE-2019-15971 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-15971 being exploited?

There is no known exploitation of CVE-2019-15971 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Email Security Appliance (ESA)

- [CVE-2016-6406](https://insights.sbomify.com/CVE-2016-6406/): Auth bypass in n/a (critical 9.8)
- [CVE-2018-15453](https://insights.sbomify.com/CVE-2018-15453/): Cisco Email Security Appliance Memory Corruption Denial of Service Vulnerability (high 8.6)
- [CVE-2017-6671](https://insights.sbomify.com/CVE-2017-6671/): Security feature bypass in Cisco Email Security Appliance (high 7.5)
- [CVE-2016-6458](https://insights.sbomify.com/CVE-2016-6458/): Security feature bypass in Cisco AsyncOS 10.0.0-125 and 9.7.1-066 (high 7.5)
- [CVE-2019-12706](https://insights.sbomify.com/CVE-2019-12706/): Cisco Email Security Appliance Filter Bypass Vulnerability (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-15971 and fix it if it is affected.

What it is: CVE-2019-15971 is a medium-severity vulnerability in Cisco Email Security Appliance (ESA), published on 26 Nov 2019. 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-2019-15971 in the wild and no public exploit code.

Affected product: Cisco Email Security Appliance (ESA). 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-2019-15971/ (Markdown: https://insights.sbomify.com/CVE-2019-15971/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-15971
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-15971
- OSV: https://osv.dev/vulnerability/CVE-2019-15971

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From sbomify Insights: https://insights.sbomify.com/CVE-2019-15971/
Summaries are generated and may contain mistakes; the official description above is the record.