Palo Alto Networks PAN-OS: Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
› Palo Alto Networks PAN-OS
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- started
- May 6, 2026
- closed
- May 6, 2026
- CVEs
- 1
- sources
- 3
## summary
Palo Alto Networks PAN-OS contains an out-of-bounds write vulnerability in the User-ID Authentication Portal (aka Captive Portal) service that can allow an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets. Added to CISA KEV on 2026-05-06.
severity: Actively exploited (CISA KEV)
## cve ids[1]
## affected
- See vendor advisory / CISA notes (versions not always listed in KEV feed)
## fixed in
- See vendor advisory linked in sources
## timeline[1]
CISA added CVE-2026-0300 to the KEV catalog (due 2026-05-09).
## advisories[2]
## news & write-ups[1]
## notes & caveats
Derived from CISA KEV JSON feed catalogVersion 2026.10.21. Exact affected/fixed version strings are not always in the KEV record — verify against the vendor advisory URL. startedAt uses dateAdded (exploitation may have begun earlier).
