# CVE-2022-20737: Cisco Adaptive Security Appliance Software Clientless SSL VPN Heap Overflow Vulnerability

> An authenticated attacker can cause a denial of service or read sensitive memory via a heap overflow in the Clientless SSL VPN portal.

- **Severity:** High 8.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 May 2022
- **Updated:** 6 Nov 2024
- **Also known as:** GHSA-m263-3fx7-gm9v

## What is CVE-2022-20737?

CVE-2022-20737 is a high-severity memory corruption vulnerability in Cisco Adaptive Security Appliance Software, published on 3 May 2022. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability in the handler for HTTP authentication for resources accessed through the Clientless SSL VPN portal of Cisco Adaptive Security Appliance (ASA) Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on an affected device or to obtain portions of process memory from an affected device. This vulnerability is due to insufficient bounds checking when parsing specific HTTP authentication messages. An attacker could exploit this vulnerability by sending malicious traffic to an affected device acting as a VPN Gateway. To send this malicious traffic, an attacker would need to control a web server that can be accessed through the Clientless SSL VPN portal. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition, or to retrieve bytes from the device process memory that may contain sensitive information.

Weakness: CWE-787 (Out-of-bounds Write), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2022-20737?

It affects 1 product.


Products: Cisco Adaptive Security Appliance Software.

## How do I fix CVE-2022-20737?

No fix has been published for CVE-2022-20737 yet. Limit exposure of the affected software until one is available.

## Is CVE-2022-20737 being exploited?

There is no known exploitation of CVE-2022-20737 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-2022-20737 and fix it if it is affected.

What it is: CVE-2022-20737 is a high-severity memory corruption vulnerability in Cisco Adaptive Security Appliance Software, published on 3 May 2022. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2022-20737 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-2022-20737/ (Markdown: https://insights.sbomify.com/CVE-2022-20737/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-20737
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-20737
- OSV: https://osv.dev/vulnerability/CVE-2022-20737

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From sbomify Insights: https://insights.sbomify.com/CVE-2022-20737/
Summaries are generated and may contain mistakes; the official description above is the record.