CVE-2026-0300: Palo Alto Networks PAN-OS Out-of-bounds Write Vulnerability
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
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.
Description quoted from the CVE record (assigned by palo_alto, published 2026-05-06).
Weakness: CWE-787: Out-of-bounds Write
How it can be exploited
Exploitable over the network with low attack complexity with no special attack requirements needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:N/E:A/AU:Y/R:U/V:C/RE:M/U:Red
CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.
- On CISA KEV since
- 2026-05-06
- US federal deadline
- 2026-05-09
- Ransomware use
- Not known
Public exploit evidence (Exploit Observer)
Also known as: BDU:2026-06322, EUVD-2026-27879, GHSA-3vfh-3cpw-2378
VEDAS cluster: VEDAS:GAUSSGATE
Exploit Observer links 11 pieces of public exploit code or detection modules that name this CVE or one of its aliases.
Exploit code and modules (11)
Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.
- Code repository: https://github.com/0xblackash/cve-2026-0300
- Code repository: https://github.com/bannned-bit/cve-2026-0300-panos
- Code repository: https://github.com/bytewraith1/cve-2026-0300
- Code repository: https://github.com/lu4m575/cve-2026-0300
- Code repository: https://github.com/matad0r-maghribi/cve-2026-0300-panos
- Code repository: https://github.com/mr-r3b00t/cve-2026-0300
- Code repository: https://github.com/p3nt3st3r-star/cve-2026-0300-poc
- Code repository: https://github.com/ridhinva/cve-2026-0300-panos-rce
- Code repository: https://github.com/sam00/poc-cve-2026-0300-exploit
- Code repository: https://github.com/shizuku198411/cve-2026-0300
- Code repository: https://github.com/tailwindrg/cve-2026-0300-audit
Research and write-ups (1)
- Research or write-up: https://undercodetesting.com/patch-now-critical-pan-os-0-day-cve-2026-0300-grants-full-root-access-to-palo-alto-firewalls-no-password-required-video
Vulnerability databases and vendor advisories (5)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-27879
- Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-3vfh-3cpw-2378
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-0300
- Vulnerability database or vendor advisory: https://security.paloaltonetworks.com/CVE-2026-0300
- Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-0300
9 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.417
likely to be attacked soon - VEDAS
- 0.983
strong exploit evidence - On CISA KEV
- Yes, since 2026-05-06
- Detection rule
- None yet
Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| Palo Alto Networks Cloud NGFW | Not stated | All is not affected |
| Palo Alto Networks PAN-OS | from 12.1.0 before 12.1.7 from 11.2.0 before 11.2.12 from 11.1.0 before 11.1.15 from 10.2.0 before 10.2.18-h6 | Not stated |
| Palo Alto Networks Prisma Access | Not stated | All is not affected |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
Exploit Observer also maps it to: palo_alto_networks_inc. pan-os, paloaltonetworks pan-os.
How to fix it
Fixed versions stated in the CVE record: 12.1.7, 11.2.12, 11.1.15, 10.2.18-h6.
CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Until the vendor releases an official fix, the following workaround should be implemented: - Restrict User-ID Authentication Portal access to only trusted zones. - Disable User-ID Authentication Portal if not required. 5/13/2026: Palo Alto has released a variety of patches. If these are relevant to your environment, please apply the designated patch.
Vendor guidance:
- https://security.paloaltonetworks.com/CVE-2026-0300 (vendor-advisory)
How to detect it
There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.
Advisories on this CVE
- PAN-OS GlobalProtect auth bypass (CVE-2026-0257) (14 Oct 2026)
References
Vendor advisories and patches
- https://security.paloaltonetworks.com/CVE-2026-0300 (vendor-advisory)
Government sources
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-0300 (government-resource)
Other references
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.