# CVE-2021-1493: Memory corruption in Cisco Adaptive Security Appliance (ASA) Software

> An authenticated remote attacker can trigger a buffer overflow in Cisco ASA/FTD web services, causing device reload or data disclosure.

- **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:** 29 Apr 2021
- **Updated:** 8 Nov 2024
- **Also known as:** GHSA-4f73-r2j2-j4h5

## What is CVE-2021-1493?

CVE-2021-1493 is a high-severity memory corruption vulnerability in Cisco Adaptive Security Appliance Software, published on 29 Apr 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker to cause a buffer overflow on an affected system. The vulnerability is due to insufficient boundary checks for specific data that is provided to the web services interface of an affected system. An attacker could exploit this vulnerability by sending a malicious HTTP request. A successful exploit could allow the attacker to cause a buffer overflow condition on the affected system, which could disclose data fragments or cause the device to reload, resulting in a denial of service (DoS) condition.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2021-1493?

It affects 2 products.


Products: Cisco Adaptive Security Appliance Software, Cisco Secure Firewall Threat Defense.

## How do I fix CVE-2021-1493?

No fix has been published for CVE-2021-1493 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-1493 being exploited?

There is no known exploitation of CVE-2021-1493 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-2021-1493 and fix it if it is affected.

What it is: CVE-2021-1493 is a high-severity memory corruption vulnerability in Cisco Adaptive Security Appliance Software, published on 29 Apr 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-1493 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-2021-1493/ (Markdown: https://insights.sbomify.com/CVE-2021-1493/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-1493
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1493
- OSV: https://osv.dev/vulnerability/CVE-2021-1493

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-1493/
Summaries are generated and may contain mistakes; the official description above is the record.