Quick answer
Direct answer
Risk scores
| CVSS metric | What it means |
|---|---|
| Attack vector (AV:N) | Network: reachable remotely |
| Attack complexity (AC:L) | Low complexity |
| Attack requirements (AT:N) | No attack requirements |
| Privileges required (PR:N) | No privileges required |
| User interaction (UI:N) | No user interaction |
| Confidentiality (VC:H) | High confidentiality impact |
| Integrity (VI:H) | High integrity impact |
| Availability (VA:H) | High availability impact |
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:C/RE:M/U:Red
CISA required action
About Palo Alto Networks PAN-OS
CVE-2026-0300 affects Palo Alto Networks PAN-OS, a product from Palo Alto Networks. Before acting, confirm where Palo Alto Networks PAN-OS runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.
What the flaw is
In plain terms: 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.
The weakness class is Out of Bounds Write. The program writes past the end of a buffer, a common path to code execution.
Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. It is listed in the CISA Known Exploited Vulnerabilities catalog, so treat it as an active threat and patch immediately.
Affected versions and timeline
| Field | Detail |
|---|---|
| Product | Palo Alto Networks PAN-OS |
| Affected versions | Pan-Os 10.2.0; Pan-Os 10.2.1; Pan-Os 10.2.2; Pan-Os 10.2.3; Pan-Os 10.2.4; Pan-Os 10.2.5; Pan-Os 10.2.6; Pan-Os 10.2.7; Pan-Os 10.2.8; Pan-Os 10.2.9; Pan-Os 10.2.10; Pan-Os 10.2.11 |
| Published | May 6, 2026 |
| Last modified | Jun 17, 2026 |
| Added to CISA KEV | May 6, 2026 |
| Assigning CNA | psirt@paloaltonetworks.com |
How to detect it
- Inventory every instance of Palo Alto Networks PAN-OS and record the running version against the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
- Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.
How to fix it
- Apply the fixed version of Palo Alto Networks PAN-OS named in the vendor advisory.
- If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
- Rescan after the change to prove the exposure is gone, then close the ticket.
CTEM action plan
| CTEM stage | What to do for this CVE |
|---|---|
| Scope | Add every business service that depends on Palo Alto Networks PAN-OS to the current CTEM cycle. |
| Discover | Find all instances, including shadow and cloud deployments, and record versions and exposure. |
| Prioritize | Known exploited, so top priority. |
| Validate | Confirm the flaw is reachable and exploitable in your environment and that compensating controls work. |
| Mobilize | Assign the fix to the asset owner with a due date matched to the priority, then verify closure. |
CWE References
- CWE-787: Out of Bounds Write More CVEs with this weakness
Technical References
Frequently asked questions
Related CVEs
A remote code execution (RCE) vulnerability in the management interface of Palo Alto Networks PAN-OS® software enables an authenticated attacker with network access to execute arbitrary code with root privileges on the firewall. The security risk posed by this issue is minimized by restricting access to the management interface to only trusted internal IP addresses according to our recommended best practice deployment guidelines https://live.paloaltonetworks.com/t5/community-blogs/tips-amp-tricks-how-to-secure-the-management-access-of-your-palo/ba-p/464431 . This issue is applicable to PAN-OS software on PA-Series and VM-Series firewalls and on Panorama (virtual and M-Series). Cloud NGFW and Prisma® Access are not impacted by this vulnerability.
Authentication bypass vulnerabilities in the GlobalProtect portal and gateway of Palo Alto Networks PAN-OS® software allows the attacker to bypass security restrictions and establish an unauthorized VPN connection. Panorama and Cloud NGFW are not impacted by these issues.
Out-of-bounds Write, Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') vulnerability in azerothcore azerothcore-wotlk (deps/zlib modules). This vulnerability is associated with program files inflate.C. This issue affects azerothcore-wotlk: through v4.0.0.
There is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.
Kitty is a cross-platform GPU based terminal. In versions 0.46.2 and below, the handle_compose_command() function in kitty/graphics.c performs bounds validation on composition offsets using unsigned 32-bit arithmetic that is subject to integer wrapping, potentially leading to Heap Buffer Over-Read/Write. An attacker who can write escape sequences to a kitty terminal (e.g., via a malicious file, SSH login banner, or piped content) can supply crafted x_offset/y_offset values that pass the bounds check after wrapping but cause massive out-of-bounds heap memory access in compose_rectangles(). No user interaction is required. No non-default configuration is required. The attacker only needs the ability to produce output in a kitty terminal window. This issue has been fixed in version 0.47.0.
In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: add bounds checks in nvmet_tcp_build_pdu_iovec nvmet_tcp_build_pdu_iovec() could walk past cmd->req.sg when a PDU length or offset exceeds sg_cnt and then use bogus sg->length/offset values, leading to _copy_to_iter() GPF/KASAN. Guard sg_idx, remaining entries, and sg->length/offset before building the bvec.
Earn your free CTEM certification.
Learn to scope, prioritize, validate and mobilize fixes for CVEs like CVE-2026-0300 with a free CTEM certification.
Beginner / Practitioner / Program Leader
Explore certifications