U.S. CISA adds a flaw in Palo Alto Networks PAN-OS to its Known Exploited Vulnerabilities catalog
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2026-0300 | Unauthenticated Out-of-bounds Write RCE in Palo Alto Networks PAN-OS Palo Alto Networks PAN-OS contains an out-of-bounds write vulnerability (CWE-787) in the User-ID Authentication Portal, also known as the Captive Portal service. An unauthenticated attacker can trigger the flaw by sending specially crafted packets to the portal, without needing valid credentials. Successful exploitation allows the attacker to execute arbitrary code with root privileges on the firewall, giving full control of PA-Series and VM-Series devices. Any organization running PA-Series or VM-Series firewalls with the User-ID Authentication Portal service enabled is affected. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2026-05-06, indicating exploitation in the wild; EPSS puts the 30-day exploitation probability at 31.7% (98th percentile), patches were released on 2026-05-13, no public PoC is known, and CVSS scoring is not yet available. Do: Apply the PAN-OS patches Palo Alto Networks released on 5/13/2026, prioritizing internet-facing PA-Series and VM-Series firewalls. As an interim mitigation, restrict User-ID Authentication Portal access to trusted zones only, or disable the service entirely if it is not required. Inventory your deployments for use of the Captive Portal/User-ID Authentication Portal and follow CISA KEV and BOD 22-01 requirements, including for affected cloud service instances; note that federal agencies face KEV remediation deadlines. | 9.3 | 32% | KEV |
| large≈100,000+ PAN-OS firewall deployments; the vulnerable subset (installs with the User-ID Authentication Portal enabled) is likely in the tens of thousands,… |
Full article527 words · extracted from securityaffairs.com · click to collapse
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) adds a flaw in Palo Alto Networks PAN-OS to its Known Exploited Vulnerabilities catalog
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added a flaw in the Palo Alto Networks PAN-OS, tracked as CVE-2026-0300 (CVSS score of 9.3), to its Known Exploited Vulnerabilities (KEV) catalog.
The flaw is a buffer overflow that allows unauthenticated remote code execution, especially when the User-ID portal is exposed to the internet.
“A buffer overflow vulnerability in the User-ID™ Authentication Portal (aka Captive Portal) service of Palo Alto Networks PAN-OS software allows an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets.” reads the advisory published by Palo Alto Networks. “The risk of this issue is greatly reduced if you secure access to the User-ID™ Authentication Portal per the best practice guidelines by restricting access to only trusted internal IP addresses.”
This week, Palo Alto Networks has warned that the critical PAN-OS vulnerability CVE-2026-0300 is actively exploited in the wild.
Below is the list of impacted products:
| Versions | Affected | Unaffected |
|---|---|---|
| Cloud NGFW | None | All |
| PAN-OS 12.1 | < 12.1.4-h5 < 12.1.7 | >= 12.1.4-h5 (ETA: 05/13) >= 12.1.7 (ETA: 05/28) |
| PAN-OS 11.2 | < 11.2.4-h17 < 11.2.7-h13 < 11.2.10-h6 < 11.2.12 | >= 11.2.4-h17 (ETA: 05/28) >= 11.2.7-h13 (ETA: 05/13) >= 11.2.10-h6 (ETA: 05/13) >= 11.2.12 (ETA: 05/28) |
| PAN-OS 11.1 | < 11.1.4-h33 < 11.1.6-h32 < 11.1.7-h6 < 11.1.10-h25 < 11.1.13-h5 < 11.1.15 | >= 11.1.4-h33 (ETA: 05/13) >= 11.1.6-h32 (ETA: 05/13) >= 11.1.7-h6 (ETA: 05/28) >= 11.1.10-h25 (ETA: 05/13) >= 11.1.13-h5 (ETA: 05/13) >= 11.1.15 (ETA: 05/28) |
| PAN-OS 10.2 | < 10.2.7-h34 < 10.2.10-h36 < 10.2.13-h21 < 10.2.16-h7 < 10.2.18-h6 | >= 10.2.7-h34 (ETA: 05/28) >= 10.2.10-h36 (ETA: 05/13) >= 10.2.13-h21 (ETA: 05/28) >= 10.2.16-h7 (ETA: 05/28) >= 10.2.18-h6 (ETA: 05/13) |
| Prisma Access | None | All |
The cybersecurity vendor states that the issue doesn’t impact Prisma Access, Cloud NGFW and Panorama appliances.
Palo Alto Networks says the flaw is being exploited in a limited way, mainly against systems where the User-ID Authentication Portal is exposed to the public internet.
The flaw remains unpatched, with fixes expected from May 13, 2026. It affects PA-Series and VM-Series firewalls using the User-ID Authentication Portal. Palo Alto Networks notes risk is much lower for organizations that follow best practices, like limiting access to trusted internal networks only.
“Limited exploitation has been observed targeting Palo Alto Networks User-ID™ Authentication Portals that are exposed to untrusted IP addresses and/or the public internet.” concludes the advisory. “Customers following standard security best practices, such as restricting sensitive portals to trusted internal networks are at a greatly reduced risk.”
According to Binding Operational Directive (BOD) 22-01: Reducing the Significant Risk of Known Exploited Vulnerabilities, FCEB agencies have to address the identified vulnerabilities by the due date to protect their networks against attacks exploiting the flaws in the catalog.
Experts also recommend that private organizations review the Catalog and address the vulnerabilities in their infrastructure.
CISA orders federal agencies to fix the vulnerability by May 9, 2026.
Follow me on Twitter: @securityaffairs and Facebook and Mastodon
(SecurityAffairs – hacking, US CISA Known Exploited Vulnerabilities catalog)
Text extracted automatically; images, tables and formatting may be missing. Original: https://securityaffairs.com/191780/security/u-s-cisa-adds-a-flaw-in-palo-alto-networks-pan-os-to-its-known-exploited-vulnerabilities-catalog.html