# CVE-2021-34787: Security feature bypass in Cisco Adaptive Security Appliance (ASA) Software

> Remote attackers can bypass ACL rules and security protections on Cisco ASA/FTD devices configured with object group search.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Oct 2021
- **Updated:** 7 Nov 2024
- **Also known as:** GHSA-9jgg-4q8x-859v

## What is CVE-2021-34787?

CVE-2021-34787 is a medium-severity vulnerability in Cisco Adaptive Security Appliance, published on 27 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the identity-based firewall (IDFW) rule processing feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass security protections. This vulnerability is due to improper handling of network requests by affected devices configured to use object group search. An attacker could exploit this vulnerability by sending a specially crafted network request to an affected device. A successful exploit could allow the attacker to bypass access control list (ACL) rules on the device, bypass security protections, and send network traffic to unauthorized hosts.

Weakness: CWE-755 (Improper Handling of Exceptional Conditions), CWE-183 (Permissive List of Allowed Inputs)

## Which versions are affected by CVE-2021-34787?

It affects 11 products.


Products: Cisco Adaptive Security Appliance, Cisco Adaptive Security Appliance Software, Cisco Asa 5505 Firmware, Cisco Asa 5512-X Firmware, Cisco Asa 5515-X Firmware, Cisco Asa 5525-X Firmware, Cisco Asa 5545-X Firmware, Cisco Asa 5555-X Firmware, Cisco Asa 5580 Firmware, Cisco Asa 5585-X Firmware, Cisco Secure Firewall Threat Defense.

## How do I fix CVE-2021-34787?

No fix has been published for CVE-2021-34787 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-34787 being exploited?

There is no known exploitation of CVE-2021-34787 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Adaptive Security Appliance

- [CVE-2021-1573](https://insights.sbomify.com/CVE-2021-1573/): Denial of service in Cisco Adaptive Security Appliance Software (high 8.6)
- [CVE-2021-34793](https://insights.sbomify.com/CVE-2021-34793/): Denial of service in Cisco Adaptive Security Appliance (ASA) Software (high 8.6)
- [CVE-2021-40117](https://insights.sbomify.com/CVE-2021-40117/): Denial of service in Cisco Adaptive Security Appliance (ASA) Software (high 8.6)
- [CVE-2021-40118](https://insights.sbomify.com/CVE-2021-40118/): Denial of service in Cisco Adaptive Security Appliance (ASA) Software (high 8.6)
- [CVE-2020-3304](https://insights.sbomify.com/CVE-2020-3304/): Denial of service in Cisco Adaptive Security Appliance (ASA) Software (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-34787 and fix it if it is affected.

What it is: CVE-2021-34787 is a medium-severity vulnerability in Cisco Adaptive Security Appliance, published on 27 Oct 2021. 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-2021-34787 in the wild and no public exploit code.

Affected product: Cisco Adaptive Security Appliance. 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-2021-34787/ (Markdown: https://insights.sbomify.com/CVE-2021-34787/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34787
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34787
- OSV: https://osv.dev/vulnerability/CVE-2021-34787

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-34787/
Summaries are generated and may contain mistakes; the official description above is the record.