CVE-2026-7686 eyeo Adblock Plus Legacy Premium Activation premium.preload.js postMessage access control
Attackers can bypass access controls in the legacy premium activation flow to obtain temporary premium features via postMessage manipulation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-7686?
CVE-2026-7686 is a medium-severity missing authorization vulnerability in eyeo Adblock Plus, published on 3 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability was found in eyeo Adblock Plus up to 4.36.2 on Chrome. Affected by this vulnerability is the function postMessage of the file premium.preload.js of the component Legacy Premium Activation. Performing a manipulation results in improper access controls. Remote exploitation of the attack is possible. The exploit has been made public and could be used. Upgrading the affected component is recommended. 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."
Which versions are affected by CVE-2026-7686?
How do I fix CVE-2026-7686?
No fix has been published for CVE-2026-7686 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-7686 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-7686 exists.
Sources
Also known as GHSA-hjhr-m4xv-543v.