# CVE-2019-1873: Cisco ASA and FTD Software Cryptographic TLS and SSL Driver Denial of Service Vulnerability

> Remote attackers can cause Cisco ASA and FTD devices to reboot by sending crafted TLS/SSL packets, resulting in a denial of service.

- **Severity:** High 8.6 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/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:** 10 Jul 2019
- **Updated:** 19 Nov 2024
- **Also known as:** GHSA-q443-v72w-7x2v

## What is CVE-2019-1873?

CVE-2019-1873 is a high-severity denial of service vulnerability in Cisco Adaptive Security Appliance (ASA) Software, published on 10 Jul 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the cryptographic driver for Cisco Adaptive Security Appliance Software (ASA) and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reboot unexpectedly. The vulnerability is due to incomplete input validation of a Secure Sockets Layer (SSL) or Transport Layer Security (TLS) ingress packet header. An attacker could exploit this vulnerability by sending a crafted TLS/SSL packet to an interface on the targeted device. An exploit could allow the attacker to cause the device to reload, which will result in a denial of service (DoS) condition. Note: Only traffic directed to the affected system can be used to exploit this vulnerability. This vulnerability affects systems configured in routed and transparent firewall mode and in single or multiple context mode. This vulnerability can be triggered by IPv4 and IPv6 traffic. A valid SSL or TLS session is required to exploit this vulnerability.

Weakness: CWE-20 (Improper Input Validation), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2019-1873?

It affects 5 products.


Products: Cisco Asa 5506-X Firmware, Cisco Asa 5506h-X Firmware, Cisco Asa 5506w-X Firmware, Cisco Asa 5508-X Firmware, Cisco Asa 5516-X Firmware.

## How do I fix CVE-2019-1873?

No fix has been published for CVE-2019-1873 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-1873 being exploited?

There is no known exploitation of CVE-2019-1873 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-1873 and fix it if it is affected.

What it is: CVE-2019-1873 is a high-severity denial of service vulnerability in Cisco Adaptive Security Appliance (ASA) Software, published on 10 Jul 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-2019-1873 in the wild and no public exploit code.

Affected product: Cisco Adaptive Security Appliance (ASA) Software. 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-2019-1873/ (Markdown: https://insights.sbomify.com/CVE-2019-1873/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-1873
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1873
- OSV: https://osv.dev/vulnerability/CVE-2019-1873

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From sbomify Insights: https://insights.sbomify.com/CVE-2019-1873/
Summaries are generated and may contain mistakes; the official description above is the record.