eyeo Adblock Plus up to 4.36.2 on Chrome Legacy Premium Activation premium.preload.js postMessage access control

Summaryinfo

A vulnerability was found in eyeo Adblock Plus up to 4.36.2 on Chrome. It has been declared as problematic. Affected by this issue is the function postMessage of the file premium.preload.js of the component Legacy Premium Activation. Executing a manipulation can lead to access control. This vulnerability is handled as CVE-2026-7686. The attack can be executed remotely. Additionally, an exploit exists. It is recommended to upgrade the affected component. The vendor provides additional details: "The affected code path is a legacy Premium activation flow that has been deprecated. eyeo has already migrated to a new user account-based licensing system. The exploit does not grant permanent Premium access. The licensing server issues a short-lived trial license (valid for approximately 24 hours) for any submitted userId. On the next license check, the server validates against a real subscription and the trial expires if no valid subscription is found. The researcher's claim of permanently unlocking all Premium features is therefore incorrect. (...) The old flow has been present for years and has not been weaponized at scale to our knowledge. The risk to eyeo and to users is minimal."

Detailsinfo

A vulnerability classified as problematic was found in eyeo Adblock Plus up to 4.36.2 on Chrome. This vulnerability affects the function postMessage of the file premium.preload.js of the component Legacy Premium Activation. The manipulation with an unknown input leads to a access control vulnerability. The CWE definition for the vulnerability is CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. As an impact it is known to affect integrity.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-7686. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details and also a public exploit are known. The MITRE ATT&CK project declares the attack technique as T1068.

It is possible to download the exploit at github.com. It is declared as proof-of-concept. The vendor provides additional details: "The affected code path is a legacy Premium activation flow that has been deprecated. eyeo has already migrated to a new user account-based licensing system. The exploit does not grant permanent Premium access. The licensing server issues a short-lived trial license (valid for approximately 24 hours) for any submitted userId. On the next license check, the server validates against a real subscription and the trial expires if no valid subscription is found. The researcher's claim of permanently unlocking all Premium features is therefore incorrect. (...) The old flow has been present for years and has not been weaponized at scale to our knowledge. The risk to eyeo and to users is minimal."

Upgrading eliminates this vulnerability. The upgrade is hosted for download at adblockplus.org.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-26824). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

• eyeo

Name

• Adblock Plus

Version

• 4.36.0
• 4.36.1
• 4.36.2

CPE 2.3info

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CPE 2.2info

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Submitinfo

Accepted

• Submit #793551: Eyeo GmbH Adblock Plus 4.36.2 Privilege Escalation (by DRXYJ)

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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