CVE-2021-3055

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.

Overview

State

—

Assigner (CNA)

—

CVSS severity

MEDIUM

CVSS score

5.0 / 10

CVSS vector

AV:N/AC:L/Au:S/C:P/I:N/A:C

Effective score

5.0 / 10 MEDIUM source: CNA overview

CWE(s)

—

Reserved

—

Published

2021-09-08 00:00 UTC

Last updated

—

Source

https://www.rapid7.com/db/vulnerabilities/panos-cve-2021-3055/

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published

2021-09-08 17:15:12 UTC

NVD last modified

2024-11-21 06:20:51 UTC

NVD CVSS v3.1

6.5 / 10 MEDIUM source: psirt@paloaltonetworks.com

NVD CVSS vector

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

Exploitability subscore

1.2 / 10

Impact subscore

5.2 / 10

EPSS score

0.0028 (probability of exploitation in next 30 days)

EPSS percentile

51.78% vs all CVEs — higher = more likely to be exploited, as of 2026-06-04

NVD-assigned CWE(s): CWE-611 (differs from the CNA list above)

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID

EUVD-2021-26407

Assigner

palo_alto

Published

Sep 8, 2021, 5:10:22 PM

Updated

Sep 17, 2024, 12:30:33 AM

EUVD base score (CVSS 3.1)

6.5 / 10
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H

EUVD-reported EPSS

0.2800

Vendors

Palo Alto Networks

Products

PAN-OS (9.0 <9.0.14)

PAN-OS (9.1 <9.1.10)

PAN-OS (8.1 <8.1.20)

PAN-OS (10.0 <10.0.6)

Aliases

GHSA-q695-424c-rgvg

ENISA 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.

Vendor references (0)

References embedded in the original CVE record by the assigning CNA.

None in the CVE record.

Web references (3)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

• https://attackerkb.com/topics/CVE-2021-3055 rapid7:attackerkb.com
• https://security.paloaltonetworks.com/CVE-2021-3055 rapid7:security.paloaltonetworks.com
• https://www.cve.org/CVERecord?id=CVE-2021-3055 rapid7:www.cve.org

• Security Updates - Red Hat Customer Portal
  web:access.redhat.com

  Learn about our open source products, services, and company. You are here

  2026-06-04 02:02 UTC
• Update Software, Mitigation M1051 - Enterprise | MITRE ATT&CK®
  web:attack.mitre.org

  This mitigation can be implemented through the following measures: Regular Operating System Updates Implementation: Apply the latest Windows security updates monthly using WSUS (Windows Server Update Services) or a similar patch management solution. Configure systems to check for updates automatically and schedule reboots during maintenance ...

  2026-06-04 02:02 UTC
• Windows 11, version 25H2 known issues and notifications
  web:learn.microsoft.com

  Windows 11, version 25H2 is now available for all eligible devices. Devices running Home and Pro editions of Windows 11 that are not managed by IT departments will receive the update to Windows 11, version 25H2 through the machine learning-based intelligent rollout.

  2026-06-04 02:02 UTC
• NVD - Home
  web:nvd.nist.gov

  The NVD is the U.S. government repository of standards based vulnerability management data represented using the Security Content Automation Protocol (SCAP). This data enables automation of vulnerability management, security measurement, and compliance. The NVD includes databases of security checklist references, security-related software flaws, product names, and impact metrics. For ...

  2026-06-04 02:02 UTC
• Security Update Guide - Microsoft
  web:portal.msrc.microsoft.com

  The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

  2026-06-04 02:02 UTC
• Android Security Bulletin—November 2025 - Android Open Source Project
  web:source.android.com

  Android partners are encouraged to fix all issues in this bulletin and use the latest security patch level. Devices that use the 2025-11-01 security patch level must include all issues associated with that security patch level, as well as fixes for all issues reported in previous security bulletins.

  2026-06-04 02:02 UTC
• Oracle Critical Patch Update Advisory - April 2025
  web:www.oracle.com

  Oracle Critical Patch Update Advisory - April 2025 Description A Critical Patch Update is a collection of patches for multiple security vulnerabilities. These patches address vulnerabilities in Oracle code and in third party components included in Oracle products. These patches are usually cumulative, but each advisory describes only the security patches added since the previous Critical Patch ...

  2026-06-04 02:02 UTC
• Oracle Critical Patch Update Advisory - October 2025
  web:www.oracle.com

  This Critical Patch Update contains 374 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at October 2025 Critical Patch Update: Executive Summary and Analysis.

  2026-06-04 02:02 UTC
• Windows 11's Secure Boot fix update finally rolls out to ... - PCWorld
  web:www.pcworld.com

  Windows 11's Secure Boot fix update finally rolls out to more PCs Important security certificates for Windows 11 will soon expire for many users.

  2026-06-04 02:02 UTC
• Patch Tuesday June 2026: Security Updates & CVE Analysis
  web:zecurit.com

  Get the complete breakdown of Microsoft's June 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

  2026-06-04 02:02 UTC

Only Available for Registered Users. Sign in to view.