CISA KEV Critical Cryptography

CVE-2020-2021 — Palo Alto Networks PAN-OS Authentication Bypass Vulnerability

When Security Assertion Markup Language (SAML) authentication is enabled and the 'Validate Identity Provider Certificate' option is disabled (unchecked), improper verification of signatures in PAN-OS SAML authentication enables an unauthenticated network-based attacker to access protected resources. The attacker must have network access to the vulnerable server to exploit this vulnerability. This issue affects PAN-OS 9.1 versions earlier than PAN-OS 9.1.3; PAN-OS 9.0 versions earlier than PAN-OS 9.0.9; PAN-OS 8.1 versions earlier than PAN-OS 8.1.15, and all versions of PAN-OS 8.0 (EOL). This issue does not affect PAN-OS 7.1. This issue cannot be exploited if SAML is not used for authentication. This issue cannot be exploited if the 'Validate Identity Provider Certificate' option is enabled (checked) in the SAML Identity Provider Server Profile. Resources that can be protected by SAML-based single sign-on (SSO) authentication are: GlobalProtect Gateway, GlobalProtect Portal, GlobalProtect Clientless VPN, Authentication and Captive Portal, PAN-OS next-generation firewalls (PA-Series, VM-Series) and Panorama web interfaces, Prisma Access In the case of GlobalProtect Gateways, GlobalProtect Portal, Clientless VPN, Captive Portal, and Prisma Access, an unauthenticated attacker with network access to the affected servers can gain access to protected resources if allowed by configured authentication and Security policies. There is no impact on the integrity and availability of the gateway, portal or VPN server. An attacker cannot inspect or tamper with sessions of regular users. In the worst case, this is a critical severity vulnerability with a CVSS Base Score of 10.0 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N). In the case of PAN-OS and Panorama web interfaces, this issue allows an unauthenticated attacker with network access to the PAN-OS or Panorama web interfaces to log in as an administrator and perform administrative actions. In the worst-case scenario, this is a critical severity vulnerability with a CVSS Base Score of 10.0 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H). If the web interfaces are only accessible to a restricted management network, then the issue is lowered to a CVSS Base Score of 9.6 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H). Palo Alto Networks is not aware of any malicious attempts to exploit this vulnerability.

Published Jun 29, 2020 · Updated Oct 13, 2026 · Sources: CISA Known Exploited Vulnerabilities, CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database, GitHub Security Advisories · CNA: palo_alto

Urgent

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

CISA KEV · Mar 25, 2022 R used by ransomware (CISA) Proofs of concept on GitHub · 1

How the score was calculated

Confirmed exploitation (CISA KEV)+35
Used in ransomware campaigns (CISA)+10
Public exploit/PoC (github)+6
EPSS 4.4% (30-day exploitation probability)+14
Technical severity (critical)+10
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Confirmed

CISA KEV, listed Mar 25, 2022

EPSS FIRST

4.36%

ahead of 91% of scored CVEs · Oct 14, 2026

Affects

Palo Alto Networks

PAN-OS

CVSS base

10.0

Critical · 4 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Active

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented mitigation — security.paloaltonetworks.com (NIST National Vulnerability Database)

CISA required action CISA

Apply updates per vendor instructions.

US federal deadline: Apr 15, 2022 — passed 1644 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Palo Alto Networks PAN-OS).
Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
Apply the documented mitigations until a definitive fix is available.
EPSS ahead of 91% of scored CVEs: prioritize it in the patch queue.
Search available logs for exploit probes matching the vulnerability class (cryptography), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Palo Alto Networks	PAN-OS	version 8.0.*≥ 8.1 and < 8.1.15≥ 9.0 and < 9.0.9≥ 9.1 and < 9.1.3	Vulnerable	CVE Program (cve.org) e CISA ADP
Palo Alto Networks	PAN-OS	≥ 8.0.0 and ≤ 8.0.20≥ 8.1.0 and < 8.1.15≥ 9.0.0 and < 9.0.9≥ 9.1.0 and < 9.1.3	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
10.0	CVSS 3.1	Critical	3.9	6.0	psirt@paloaltonetworks.com via NIST National Vulnerability Database
10.0	CVSS 3.1	Critical	3.9	6.0	nvd@nist.gov via NIST National Vulnerability Database
10.0	CVSS 3.1	Critical	—	—	GitHub, Inc. via GitHub Security Advisories
10.0	CVSS 3.1	Critical	—	—	palo_alto via CVE Program (cve.org) e CISA ADP
9.3	CVSS 2.0	High	8.6	10.0	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-347 · Improper Verification of Cryptographic Signature

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

Listed

Mar 25, 2022

Federal deadline

Apr 15, 2022

passed 1644 day(s) ago

Ransomware use

Known

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

Public exploits, PoCs and detection templates

Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.

Proofs of concept on GitHub

# Jozini Network Scanner Built in Termux at KwaQondile Library, Jozini KZN Tools: - scanner.py: Port scanner with banner grabbing (20 ports + report saving) - cve_check.py: Maps RouterOS version to known CVEs Finding: MikroTik RouterOS 6.46.8 vulnerable to CVE-2020-2021 (Critical) Author: [Your Na ★ 0 Sep 5, 2026

Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 4.36%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Check TLS negotiations and unexpected certificates in the component’s traffic.
Hunt retroactively in logs from before Mar 25, 2022 (KEV listing): exploitation may have started earlier.

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Fix documented
Oct 13, 2026 · NIST National Vulnerability Database
Affected products added · paloaltonetworks/pan-os
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · Published → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record published
Oct 13, 2026
Affected products added · palo alto networks/pan-os
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
CVSS changed · 10.0
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Source status changed · → Published
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Added to CISA KEV (detected)
Oct 13, 2026 · CISA Known Exploited Vulnerabilities
Record created in this database
Oct 13, 2026 · CISA Known Exploited Vulnerabilities
2022
Added to CISA KEV catalog
Mar 24, 2022 · CISA
2020
CVE published
Jun 29, 2020 · palo_alto

Source activity

Repeated readings are counted rather than listed.

3× References added · Oct 13, 2026 – Oct 13, 2026
1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

4 on the record

security.paloaltonetworks.com/CVE-2020-2021
x_refsource_MISC, Mitigation, Vendor Advisory, CVE Program (cve.org) e CISA ADP
www.cisa.gov/known-exploited-vulnerabilities-catalog
US Government Resource, NIST National Vulnerability Database
nvd.nist.gov/vuln/detail/CVE-2020-2021
GitHub Security Advisories
github.com/advisories/GHSA-84wc-9427-hw23
GitHub Security Advisories

Elsewhere on this site

Palo Alto Networks
every CVE for this vendor

2022-03
what else CISA listed that month

Cryptography
same class

CWE-347
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-0320 PAN-OS: Authenticated Admin Command Injection Vulnerability 1d
Medium CVE-2026-0318 PAN-OS: Denial of Service (DoS) on Panorama 1d
Medium CVE-2026-0319 PAN-OS: Improper Input Handling Vulnerability 1d
Low CVE-2026-0317 PAN-OS: Denial of Service Vulnerability 1d
Low CVE-2026-0316 PAN-OS: Stored Cross-Site Scripting (XSS) Vulnerability 1d
Medium CVE-2026-0321 PAN-OS: Denial of Service (DoS) Vulnerabilities in Network Services 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2020-2021 is "Palo Alto Networks PAN-OS Authentication Bypass Vulnerability", rated Critical. It affects PAN-OS (Palo Alto Networks); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 10.0 describes technical severity. EPSS 4.36% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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