# CVE-2021-1422: Denial of service in Cisco Adaptive Security Appliance (ASA) Software

> An attacker can cause a denial of service by sending malicious IPsec packets, crashing Cisco ASA and FTD devices.

- **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/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:** 16 Jul 2021
- **Updated:** 7 Nov 2024
- **Also known as:** GHSA-jcpc-3vwc-j47q

## What is CVE-2021-1422?

CVE-2021-1422 is a high-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 16 Jul 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability in the software cryptography module of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker or an unauthenticated attacker in a man-in-the-middle position to cause an unexpected reload of the device that results in a denial of service (DoS) condition. The vulnerability is due to a logic error in how the software cryptography module handles specific types of decryption errors. An attacker could exploit this vulnerability by sending malicious packets over an established IPsec connection. A successful exploit could cause the device to crash, forcing it to reload. Important: Successful exploitation of this vulnerability would not cause a compromise of any encrypted data. Note: This vulnerability affects only Cisco ASA Software Release 9.16.1 and Cisco FTD Software Release 7.0.0.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2021-1422?

It affects 2 products.


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

## How do I fix CVE-2021-1422?

No fix has been published for CVE-2021-1422 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-1422 being exploited?

There is no known exploitation of CVE-2021-1422 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-2021-1422 and fix it if it is affected.

What it is: CVE-2021-1422 is a high-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 16 Jul 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-2021-1422 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-2021-1422/ (Markdown: https://insights.sbomify.com/CVE-2021-1422/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-1422
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1422
- OSV: https://osv.dev/vulnerability/CVE-2021-1422

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-1422/
Summaries are generated and may contain mistakes; the official description above is the record.