Key points
- Prisma Browser versions from 155.16.5 up to 155.16.5.40 are vulnerable.
- The vendor has released a fix in version 155.16.5.40.
- The flaws include cross-site request forgery and missing authorization checks.
Prisma Browser versions starting from 155.16.5 and ending just before 155.16.5.40 contain multiple security vulnerabilities. Palo Alto Networks has addressed these issues by incorporating fixes from Chromium’s monthly updates. Users running any version in this range should update immediately to mitigate risk.
In plain English
The flaws stem from the Chromium engine that powers Prisma Browser. Issues include improper input validation, cross-site request forgery, and insufficient policy enforcement. Some defects allow cleartext transmission of sensitive data or incorrect authorization checks. These problems could potentially compromise user sessions or expose data if exploited by an attacker.
The background
Palo Alto Networks’ PSIRT team published advisory PAN-SA-2026-0013 to detail these vulnerabilities. The advisory links to several Chromium stable channel updates from September and October 2026. The combined severity is rated high, with a CVSS score of 7.7 for base threats and 9.4 for broader impact. No special configuration is required for a system to be affected.
What changes now
Palo Alto Networks states it is not aware of any malicious exploitation of these flaws. However, the potential for abuse remains significant given the nature of the defects. The vendor has integrated the necessary Chromium patches into its latest Prisma Browser release. Organizations must ensure their browsers are updated to version 155.16.5.40 or later.
Who needs to act first
Teams usually prioritize systems that handle sensitive customer data or internal credentials. Check whether remote workers or shared devices are running vulnerable versions. Roll out updates to exposed endpoints first, then move to internal networks. Test the new version in a small group to ensure compatibility with existing tools. Back up important browser profiles before applying the change to avoid data loss during the transition.
Background: Cross-site request forgery (CSRF)
Cross-site request forgery tricks users into executing unwanted actions on trusted sites. Protect your business by enforcing same-site cookies and validating request origins. Verify that your web applications use anti-forgery tokens and restrict sensitive operations to secure contexts.
Read the full guide: CSRF Risks and Protection: Secure Your Business Web Apps
What to do and how to stay safe: Palo Alto Networks
- Verify which Prisma Browser versions are installed on your corporate devices.
- Update all vulnerable browsers to version 155.16.5.40 or newer as soon as possible.
- Monitor network traffic for unusual activity while updates are being deployed.
- Educate users to avoid clicking suspicious links until all systems are patched.
Step-by-step guide: Out-of-Band Patches: Meaning, Risks, and Deployment Reality
General security guidance from the Patch Herald newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
Which Prisma Browser versions are affected by these flaws?
Versions from 155.16.5 up to, but not including, 155.16.5.40 are vulnerable.
Is there a fix available for these vulnerabilities?
Yes, Palo Alto Networks has released version 155.16.5.40 which includes the necessary patches.
Has this vulnerability been exploited in the wild?
Palo Alto Networks reports it is not aware of any malicious exploitation of this issue.
