# CVE-2021-3055: PAN-OS: XML External Entity (XXE) Reference Vulnerability in the PAN-OS Web Interface

> An authenticated administrator can exploit an XXE vulnerability in the PAN-OS web interface to read arbitrary files and cause a denial of service.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Sep 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-q695-424c-rgvg

## What is CVE-2021-3055?

CVE-2021-3055 is a medium-severity vulnerability in Paloaltonetworks Pan-Os, published on 8 Sep 2021. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

An improper restriction of XML external entity (XXE) reference vulnerability in the Palo Alto Networks PAN-OS web interface enables an authenticated administrator to read any arbitrary file from the file system and send a specifically crafted request to the firewall that causes the service to crash. Repeated attempts to send this request result in denial of service to all PAN-OS services by restarting the device and putting it into maintenance mode. This issue impacts: PAN-OS 8.1 versions earlier than PAN-OS 8.1.20; PAN-OS 9.0 versions earlier than PAN-OS 9.0.14; PAN-OS 9.1 versions earlier than PAN-OS 9.1.10; PAN-OS 10.0 versions earlier than PAN-OS 10.0.6. This issue does not affect Prisma Access.

Weakness: CWE-611 (Improper Restriction of XML External Entity Reference)

## Which versions are affected by CVE-2021-3055?

It affects 1 product.


Products: Paloaltonetworks Pan-Os.

## How do I fix CVE-2021-3055?

No fix has been published for CVE-2021-3055 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-3055 being exploited?

There is no known exploitation of CVE-2021-3055 in the wild and no public exploit code.

## Other vulnerabilities in Paloaltonetworks Pan-Os

- [CVE-2024-3400](https://insights.sbomify.com/CVE-2024-3400/): Palo Alto Networks PAN-OS Command Injection (critical 10.0, exploited in the wild)
- [CVE-2020-2021](https://insights.sbomify.com/CVE-2020-2021/): Palo Alto Networks PAN-OS Authentication Bypass (critical 10.0, exploited in the wild)
- [CVE-2017-15944](https://insights.sbomify.com/CVE-2017-15944/): Palo Alto Networks PAN-OS Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2026-0300](https://insights.sbomify.com/CVE-2026-0300/): Palo Alto Networks PAN-OS Out-of-bounds Write (critical 9.3, exploited in the wild)
- [CVE-2024-0012](https://insights.sbomify.com/CVE-2024-0012/): Palo Alto Networks PAN-OS Management Interface Authentication Bypass (critical 9.3, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-3055 and fix it if it is affected.

What it is: CVE-2021-3055 is a medium-severity vulnerability in Paloaltonetworks Pan-Os, published on 8 Sep 2021. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-3055 in the wild and no public exploit code.

Affected product: Paloaltonetworks Pan-Os. 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-2021-3055/ (Markdown: https://insights.sbomify.com/CVE-2021-3055/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3055
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3055
- OSV: https://osv.dev/vulnerability/CVE-2021-3055

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-3055/
Summaries are generated and may contain mistakes; the official description above is the record.