# CVE-2020-27124: Cisco Adaptive Security Appliance Software SSL/TLS Denial of Service Vulnerability

> Unauthenticated remote attackers can cause Cisco ASA devices to reload unexpectedly via malicious SSL/TLS messages, resulting in a denial of service.

- **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/RL:X/RC:X/E:X`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Nov 2024
- **Updated:** 18 Nov 2024
- **Also known as:** GHSA-j69q-qfwm-m736

## What is CVE-2020-27124?

CVE-2020-27124 is a high-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 18 Nov 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the SSL/TLS handler of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to cause the affected device to reload unexpectedly, leading to a denial of service (DoS) condition.
The vulnerability is due to improper error handling on established SSL/TLS connections. An attacker could exploit this vulnerability by establishing an SSL/TLS connection with the affected device and then sending a malicious SSL/TLS message within that connection. A successful exploit could allow the attacker to cause the device to reload.Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

Weakness: CWE-457 (Use of Uninitialized Variable)

## Which versions are affected by CVE-2020-27124?

It affects 1 product.


Products: Cisco Adaptive Security Appliance Software.

## How do I fix CVE-2020-27124?

No fix has been published for CVE-2020-27124 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-27124 being exploited?

There is no known exploitation of CVE-2020-27124 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Adaptive Security Appliance Software

- [CVE-2025-20333](https://insights.sbomify.com/CVE-2025-20333/): Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow (critical 9.9, exploited in the wild)
- [CVE-2016-6366](https://insights.sbomify.com/CVE-2016-6366/): Cisco Adaptive Security Appliance (ASA) SNMP Buffer Overflow (high 8.8, exploited in the wild)
- [CVE-2026-20349](https://insights.sbomify.com/CVE-2026-20349/): Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection (high 8.6, exploited in the wild)
- [CVE-2024-20353](https://insights.sbomify.com/CVE-2024-20353/): Cisco ASA and FTD Denial of Service (high 8.6, exploited in the wild)
- [CVE-2016-6367](https://insights.sbomify.com/CVE-2016-6367/): Cisco Adaptive Security Appliance (ASA) CLI Remote Code Execution (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-27124 and fix it if it is affected.

What it is: CVE-2020-27124 is a high-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 18 Nov 2024. 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-2020-27124 in the wild and no public exploit code.

Affected product: Cisco Adaptive Security Appliance 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-2020-27124/ (Markdown: https://insights.sbomify.com/CVE-2020-27124/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-27124
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-27124
- OSV: https://osv.dev/vulnerability/CVE-2020-27124

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-27124/
Summaries are generated and may contain mistakes; the official description above is the record.