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Pan OsOperating system · Paloaltonetworks

CVE-2021-3055

MEDIUM · 6.5 CVSS v3.1 Published 2021-09-08
Fix available
A fix is available. Upgrade to 8.1.20 / 9.0.14 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

This is an XML External Entity (XXE) injection vulnerability in the PAN-OS web interface that allows an authenticated administrator to read arbitrary files from the filesystem via specially crafted XML requests. Additionally, repeated requests cause the service to crash, leading to denial of service that requires device restart into maintenance mode.

MitigationUpgrade PAN-OS to version 8.1.20, 9.0.14, 9.1.10, 10.0.6 or later. If immediate upgrade is not possible, restrict administrative access to trusted users only and monitor for anomalous XML requests.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Pan OsOperating system
Affected:>= 8.1.0, < 8.1.20>= 9.0.0, < 9.0.14>= 9.1.0, < 9.1.10>= 10.0.0, < 10.0.6

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check PAN-OS version
    Access the web management interface and navigate to Device > Setup > Operations, or use the CLI command 'show system info' to retrieve the installed PAN-OS version
    Affected if The installed version falls within any of these ranges: 8.1.0 to before 8.1.20, 9.0.0 to before 9.0.14, 9.1.0 to before 9.1.10, or 10.0.0 to before 10.0.6
  2. Verify web interface accessibility
    Confirm that the PAN-OS web management interface (HTTPS on ports 443 or 8443) is reachable from network segments where untrusted users exist
    Affected if The web interface is exposed to network paths accessible by administrative users who are not fully trusted
  3. Identify administrative accounts
    Review the list of administrative users configured in PAN-OS under Device > Administrators, noting accounts with XML API or web UI access
    Affected if There are administrative accounts with web interface access that are not within a trusted user group
  4. Review XML request logging
    Inspect system logs and Traffic logs for anomalous XML requests, particularly those containing DOCTYPE, ENTITY, or file:// references
    Affected if Such XML requests are observed in logs originating from administrative sessions

You are affected if your PAN-OS version is below the fixed releases (8.1.20, 9.0.14, 9.1.10, 10.0.6) AND the web management interface is accessible to untrusted administrative users.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 8.1.20 / 9.0.14 / 9.1.10 or later
Fixed in 8.1.209.0.149.1.10
Interim mitigation

Upgrade PAN-OS to version 8.1.20, 9.0.14, 9.1.10, 10.0.6 or later. If immediate upgrade is not possible, restrict administrative access to trusted users only and monitor for anomalous XML requests.

Recommended fix High confidence

PAN-OS 8.1.20 or later; PAN-OS 9.0.14 or later; PAN-OS 9.1.10 or later; PAN-OS 10.0.6 or later

  1. 1. Check current PAN-OS version via Dashboard or by running 'show system info' in CLI
  2. 2. Review the upgrade path matrix at security.paloaltonetworks.com to ensure compatibility with your hardware model
  3. 3. Backup the device configuration using 'export configuration' from the Device tab
  4. 4. Download the appropriate PAN-OS update from the Palo Alto Networks Support Portal: PAN-OS 8.1.20, 9.0.14, 9.1.10, or 10.0.6 (or later)
  5. 5. Upload the update via Panorama or directly to the firewall device
  6. 6. Install the update and reboot the device
  7. 7. After reboot, verify the version with 'show system info' and confirm the fix is applied
Caveat Major version upgrades may require compatibility checks with existing Panorama, content releases, and third-party integrations; test in non-production first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Pan Os Scoped from the published advisory
  • Consultation4.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA2.0 h
11.0 hours of engineering $2,000
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-3055 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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