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Incorrect Privilege AssignmentWeakness · CWE-266

CVE-2026-7686

MEDIUM · 5.3 CVSS v3.1 Published 2026-05-03
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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."

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

An improper access control vulnerability exists in the postMessage function of premium.preload.js within the Legacy Premium Activation component of Adblock Plus up to version 4.36.2 on Chrome. Remote attackers can manipulate the userId parameter to obtain short-lived trial licenses (approximately 24 hours) rather than permanent premium access.

MitigationUpgrade to Adblock Plus version 4.36.3 or later to address the legacy premium activation vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Adblock Plus version in Chrome
    Open Chrome and navigate to chrome://extensions, enable Developer mode, find Adblock Plus and check the version number displayed under the extension name
    Affected if Version is 4.36.2 or earlier (versions 4.36.0 through 4.36.2 are affected)
  2. Locate premium.preload.js file
    Open Chrome DevTools on any page, go to the Application tab, expand Extensions in the left panel, find Adblock Plus, and look for premium.preload.js in the extension files
    Affected if The file premium.preload.js exists in the extension directory (indicating Legacy Premium Activation component is present)
  3. Inspect postMessage handler in premium.preload.js
    In Chrome DevTools Application tab, click on premium.preload.js and search for 'postMessage' or 'addEventListener' to find the message handler code
    Affected if The postMessage handler accepts and processes userId parameters without proper validation or authorization checks
  4. Verify Legacy Premium Activation feature
    Check if the extension has any premium activation functionality by examining extension permissions and background scripts
    Affected if Legacy Premium Activation component is enabled and the extension allows premium license requests through the vulnerable postMessage interface

You are affected if Adblock Plus Chrome extension version is 4.36.2 or earlier AND the premium.preload.js file with the vulnerable postMessage handler is present and active in your installation.

Generated from the published advisory. Verify against your own configuration.

Check your environment

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AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to Adblock Plus version 4.36.3 or later to address the legacy premium activation vulnerability.

Recommended fix Moderate confidence

Version newer than 4.36.2 (contact eyeo for exact fixed release number)

  1. Verify the current installed version of Adblock Plus (eyeo) in Chrome by navigating to chrome://extensions and checking the version details
  2. Contact eyeo support or check official release notes to confirm the specific version that addresses CVE-2026-7686
  3. Upgrade Adblock Plus to a version newer than 4.36.2 that includes the fix for the legacy premium activation vulnerability
  4. If automatic updates are enabled, wait for the update to propagate or manually trigger an update check in the browser extension settings
  5. After upgrading, verify the legacy premium activation flow has been removed or secured by checking that premium.preload.js no longer exposes the vulnerable postMessage function
Caveat Minimal risk - the deprecated legacy activation flow was non-functional; the new account-based licensing system should be used instead

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
4.0 hours of engineering $750
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-7686 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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