No exploitation reportedFix available

CVE-2021-3053

Q: Is CVE-2021-3053 actively exploited?

Active exploitation of CVE-2021-3053 has not been confirmed. Its EPSS score was 1.0% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-3053?

CVE-2021-3053 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

No exploitation reported by the sources we read.

Published2021-09-08
Fixed in10.0.5 · 9.1.9 · 9.0.14 · 8.1.20
WeaknessCWE-755

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2021-09-0817:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-3053?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-3053?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Palo Alto PAN-OS

Branch	Affected	Fixed in	Source
10.0	≥ 10.0.0, < 10.0.5	10.0.5	NVD
9.1	≥ 9.1.0, < 9.1.9	9.1.9	NVD
9.0	≥ 9.0.0, < 9.0.14	9.0.14	NVD
8.1	≥ 8.1.0, < 8.1.20	8.1.20	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Palo Alto PAN-OS to 10.0.5 · 9.1.9 · 9.0.14 · 8.1.20

Advisories and patches

security.paloaltonetworks.comVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CNACVSS 3.17.5read 2026-10-23
NVDCVSS 3.17.5read 2026-10-23
NVDCVSS 2.07.1read 2026-10-23
CNAweakness (CWE)CWE-755read 2026-10-23
NVDweakness (CWE)CWE-755read 2026-10-23
FIRST EPSSEPSS score1.0 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: 2021-09-08
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-3053?

Is CVE-2021-3053 actively exploited?

Active exploitation of CVE-2021-3053 has not been confirmed. Its EPSS score was 1.0% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-3053?

CVE-2021-3053 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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