CVE-2021-3055Network attack vector

File disclosure and denial of service via XXE

Published Sep 8, 2021 · Updated Sep 17, 2024

XXE in affected PAN-OS web interfaces allows remote authenticated users to read arbitrary files and crash the service via crafted requests. The web interface improperly restricts external entity references in submitted XML, allowing those references to access the firewall filesystem. Administrative web-interface access is required; repeated requests restart the device and place it in maintenance mode, interrupting all PAN-OS services.

CVSS severity6.5
Medium
EPSS probability1.07%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XXE in affected PAN-OS web interfaces allows remote authenticated users to read arbitrary files and crash the service via crafted requests. The web interface improperly restricts external entity references in submitted XML, allowing those references to access the firewall filesystem. Administrative web-interface access is required; repeated requests restart the device and place it in maintenance mode, interrupting all PAN-OS services.

The record

CVE
CVE-2021-3055
Published
Sep 8, 2021
Updated
Sep 17, 2024
Vendor
Palo Alto Networks
Product
PAN-OS
Classifications
CWE-611, T1005, T1499.004
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Sep 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0 <10.0.6 changes=[{"at":"10.0.6","status":"unaffected"}]
  2. Affected versionversion=8.1 <8.1.20 changes=[{"at":"8.1.20","status":"unaffected"}]
  3. Affected versionversion=9.0 <9.0.14 changes=[{"at":"9.0.14","status":"unaffected"}]
  4. Affected versionversion=9.1 <9.1.10 changes=[{"at":"9.1.10","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Palo Alto Networks · PAN-OSversion=10.0 <10.0.6 changes=[{"at":"10.0.6","status":"unaffected"}]; version=8.1 <8.1.20 changes=[{"at":"8.1.20","status":"unaffected"}]; version=9.0 <9.0.14 changes=[{"at":"9.0.14","status":"unaffected"}]; version=9.1 <9.1.10 changes=[{"at":"9.1.10","status":"unaffected"}]

Published CVSS scores

6.5Palo Alto NetworksCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-611Improper Restriction of XML External Entity Reference ('XXE')
T1005Data from Local System
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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