# CVE-2019-1983: Cisco Email Security Appliance and Cisco Content Security Management Appliance Denial of Service Vulnerability

> Unauthenticated remote attackers can cause repeated process crashes and service unavailability on Cisco ESA and SMA devices by sending emails with crafted attachments.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 23 Sep 2020
- **Updated:** 13 Nov 2024
- **Also known as:** GHSA-v6r4-c6r4-r649

## What is CVE-2019-1983?

CVE-2019-1983 is a high-severity denial of service vulnerability in Cisco Asyncos, published on 23 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the email message filtering feature of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) and Cisco Content Security Management Appliance (SMA) could allow an unauthenticated, remote attacker to cause repeated crashes in some internal processes that are running on the affected devices, resulting in a denial of service (DoS) condition. The vulnerability is due to insufficient input validation of email attachments. An attacker could exploit this vulnerability by sending an email message with a crafted attachment through an affected device. A successful exploit could allow the attacker to cause specific processes to crash repeatedly, resulting in the complete unavailability of both the Cisco Advanced Malware Protection (AMP) and message tracking features and in severe performance degradation while processing email. After the affected processes restart, the software resumes filtering for the same attachment, causing the affected processes to crash and restart again. A successful exploit could also allow the attacker to cause a repeated DoS condition. Manual intervention may be required to recover from this situation.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2019-1983?

It affects 3 products.


Products: Cisco Asyncos, Cisco Content Security Management Appliance, Cisco Email Security Appliance.

## How do I fix CVE-2019-1983?

No fix has been published for CVE-2019-1983 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-1983 being exploited?

There is no known exploitation of CVE-2019-1983 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-2019-1983 and fix it if it is affected.

What it is: CVE-2019-1983 is a high-severity denial of service vulnerability in Cisco Asyncos, published on 23 Sep 2020. 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-2019-1983 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-2019-1983/ (Markdown: https://insights.sbomify.com/CVE-2019-1983/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-1983
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1983
- OSV: https://osv.dev/vulnerability/CVE-2019-1983

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From sbomify Insights: https://insights.sbomify.com/CVE-2019-1983/
Summaries are generated and may contain mistakes; the official description above is the record.