CVE-2026-0300 KEV
9.8
CRITICAL · CVSS 3.1 · EPSS 31.7% (pctl 98)
Patch first
On CISA KEV — known exploited in the wild, due 2026-05-09.
Description
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. The risk of this issue is greatly reduced if you secure access to the User-ID™ Authentication Portal per the best practice guidelines https://knowledgebase.paloaltonetworks.com/KCSArticleDetail by restricting access to only trusted internal IP addresses. Prisma Access, Cloud NGFW and Panorama appliances are not impacted by this vulnerability.
Scoring
| CVSS | 9.8 (CRITICAL, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| EPSS | 31.73% — more likely to be exploited than 98% of all CVEs |
| Weakness | CWE-787 |
| On CISA KEV | yes — remediate by 2026-05-09 |
| Public exploit | none known |
| Published | 2026-05-06 |
| Last modified | 2026-06-17 |
CISA KEV
| Name | Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability |
|---|---|
| Added | 2026-05-06 |
| Due | 2026-05-09 |
| Vendor / product | Palo Alto Networks / PAN-OS |
| Ransomware use | none reported |
Affected (40)
| Vendor | Product |
|---|---|
| paloaltonetworks | pa-1410 |
| paloaltonetworks | pa-1420 |
| paloaltonetworks | pa-3410 |
| paloaltonetworks | pa-3420 |
| paloaltonetworks | pa-3430 |
| paloaltonetworks | pa-3440 |
| paloaltonetworks | pa-410 |
| paloaltonetworks | pa-410r |
| paloaltonetworks | pa-410r-5g |
| paloaltonetworks | pa-415 |
| paloaltonetworks | pa-415-5g |
| paloaltonetworks | pa-440 |
| paloaltonetworks | pa-445 |
| paloaltonetworks | pa-450 |
| paloaltonetworks | pa-450r |
| paloaltonetworks | pa-450r-5g |
| paloaltonetworks | pa-455 |
| paloaltonetworks | pa-455-5g |
| paloaltonetworks | pa-455r-5g |
| paloaltonetworks | pa-460 |
| paloaltonetworks | pa-501 |
| paloaltonetworks | pa-505 |
| paloaltonetworks | pa-510 |
| paloaltonetworks | pa-520 |
| paloaltonetworks | pa-540 |
| paloaltonetworks | pa-5410 |
| paloaltonetworks | pa-5420 |
| paloaltonetworks | pa-5430 |
| paloaltonetworks | pa-5440 |
| paloaltonetworks | pa-5445 |
| paloaltonetworks | pa-545-poe |
| paloaltonetworks | pa-5450 |
| paloaltonetworks | pa-550 |
| paloaltonetworks | pa-5540 |
| paloaltonetworks | pa-555-poe |
| paloaltonetworks | pa-5550 |
| paloaltonetworks | pa-5560 |
| paloaltonetworks | pa-5570 |
| paloaltonetworks | pa-5580 |
| paloaltonetworks | pan-os |
References
→ the Explorer · watch your stack · NVD