# CVE-2024-20526: Denial of service in Cisco Adaptive Security Appliance (ASA) Software

> Unauthenticated remote attackers can exhaust SSH resources on Cisco ASA devices, causing a denial of service for new SSH connections.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 23 Oct 2024
- **Updated:** 23 Oct 2024
- **Also known as:** GHSA-vq87-vqwh-6mj9

## What is CVE-2024-20526?

CVE-2024-20526 is a medium-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 23 Oct 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the SSH server of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition for the SSH server of an affected device.

 This vulnerability is due to a logic error when an SSH session is established. An attacker could exploit this vulnerability by sending crafted SSH messages to an affected device. A successful exploit could allow the attacker to exhaust available SSH resources on the affected device so that new SSH connections to the device are denied, resulting in a DoS condition. Existing SSH connections to the device would continue to function normally. The device must be rebooted manually to recover. However, user traffic would not be impacted and could be managed using a remote application such as Cisco Adaptive Security Device Manager (ASDM).

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2024-20526?

It affects 1 product.


Products: Cisco Adaptive Security Appliance Software.

## How do I fix CVE-2024-20526?

No fix has been published for CVE-2024-20526 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-20526 being exploited?

There is no known exploitation of CVE-2024-20526 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-2024-20526 and fix it if it is affected.

What it is: CVE-2024-20526 is a medium-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 23 Oct 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-2024-20526 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-2024-20526/ (Markdown: https://insights.sbomify.com/CVE-2024-20526/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-20526
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-20526
- OSV: https://osv.dev/vulnerability/CVE-2024-20526

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From sbomify Insights: https://insights.sbomify.com/CVE-2024-20526/
Summaries are generated and may contain mistakes; the official description above is the record.