CVE-2021-3053: PAN-OS: Exceptional Condition Denial-of-Service (DoS)

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-09-08 · updated 2026-06-17
Weakness: CWE-755

Description

An improper handling of exceptional conditions vulnerability exists in the Palo Alto Networks PAN-OS dataplane that enables an unauthenticated network-based attacker to send specifically crafted traffic through 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 9.1.9; PAN-OS 10.0 versions earlier than PAN-OS 10.0.5. This issue does not affect Prisma Access.

Affected products

Palo Alto Networks PAN-OS: from 8.1.0 before 8.1.20; from 9.0.0 before 9.0.14; from 9.1.0 before 9.1.9; from 10.0.0 before 10.0.5 — fixed in 8.1.20, 9.0.14, 9.1.9, 10.0.5
Palo Alto Networks PAN-OS: from 8.1 before 8.1.20; from 9.0 before 9.0.14; from 9.1 before 9.1.9; from 10.0 before 10.0.5 — fixed in 8.1.20, 9.0.14, 9.1.9, 10.0.5

How to fix

Upgrade to a fixed version: Palo Alto Networks PAN-OS 8.1.20, 9.0.14, 9.1.9, 10.0.5; Palo Alto Networks PAN-OS 8.1.20, 9.0.14, 9.1.9, 10.0.5. Check the vendor advisory for mitigations.

References

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