Palo Alto Networks patches high-severity Chromium flaws in Prisma Browser update

Palo Alto Networks released advisory PAN-SA-2026-0013 to notify users of high-severity vulnerabilities in its Prisma Browser. The vendor incorporated recent Chromium security fixes into the browser to address a range of issues including improper input validation and missing authorization controls.

The advisory aggregates multiple flaws found in the Chromium engine, such as cross-site request forgery in DeviceBoundSessionCredentials and insufficient policy enforcement in Extensions. Other issues include cleartext transmission of sensitive data in HttpsUpgrades and incorrect authorization in Web Authentication. These defects allow for potential unauthorized access or data exposure if exploited.

Context and Background

Palo Alto Networks assigned a CVSS-BT score of 7.7 and a CVSS-B score of 9.4 to this collection of vulnerabilities. The vendor stated that no special configuration is required for a system to be affected by these issues. This indicates that the flaws are present by default in the vulnerable versions of the software.

The company noted it is not aware of any malicious exploitation of this issue in the wild. This advisory follows a pattern of regular updates where Palo Alto Networks integrates upstream Chromium patches into its proprietary browser offerings to maintain security standards.

Who Is Affected

Prisma Browser version 155.16.5 and later versions up to, but not including, 155.16.5.40 are vulnerable to these flaws. Users running these specific builds should update their software immediately to mitigate the risk. The advisory covers fixes from several Chromium stable channel updates released in September and October 2026.

This release addresses a variety of technical defects, including uncontrolled search path elements in CredentialProvider and incorrect reference resolution in Accessibility features. Each of these issues contributes to the overall high-severity rating of the advisory.

What should you do?

Administrators should verify their current Prisma Browser version against the affected range listed in the advisory. If the version falls within the vulnerable range, they should apply the latest update provided by Palo Alto Networks. Monitoring for further advisories from the vendor is also recommended to ensure continued protection.

What to do and how to stay safe: Palo Alto Networks

• Check the installed version of Prisma Browser on all managed endpoints to see if it falls between 155.16.5 and 155.16.5.39.
• Deploy the latest available update from Palo Alto Networks to patch the identified Chromium-based vulnerabilities.
• Monitor vendor communications for any new advisories or changes to the severity rating of this issue.
• Review browser extension policies to ensure they align with the updated security controls mentioned in the advisory.

Step-by-step guide: Risk-Based Vulnerability Management: Prioritize Fixes by Actual Danger

General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.

Frequently asked questions

What is the severity rating of the Palo Alto Networks Prisma Browser vulnerability?

Palo Alto Networks rates the issue as high severity, with a CVSS-BT score of 7.7 and a CVSS-B score of 9.4.

Which versions of Prisma Browser are affected by PAN-SA-2026-0013?

Versions 155.16.5 and up to, but not including, 155.16.5.40 are vulnerable to the described flaws.

Is there evidence that these vulnerabilities are being exploited in the wild?

Palo Alto Networks stated it is not aware of any malicious exploitation of this issue.