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SecurlyApplication

CVE-2026-8879

HIGH · 7.5 CVSS v3.1 Published 2026-06-03
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
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
Version 3.0.7 of the Securly Chrome Extension dynamically registers content13.min.js as a content script via chrome.scripting.registerContentScripts() at runtime. This script is NOT declared in manifest.json and bypasses Chrome Web Store static security review. It runs on all URLs and immediately hides all page content, creates a full-page overlay, pauses all videos, and only restores content when the service worker confirms the page passes filtering. If Securly's servers are unreachable, pages remain indefinitely hidden.

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

The Securly Chrome Extension v3.0.7 uses chrome.scripting.registerContentScripts() to dynamically load a content script at runtime that is not declared in manifest.json, bypassing Chrome Web Store static security review. This script runs on all URLs, hides page content, creates a full-page overlay, pauses videos, and only restores content upon server confirmation. When servers are unreachable, pages remain hidden indefinitely, causing a denial of service.

MitigationRemove dynamic content script registration, declare all content scripts in manifest.json, implement proper error handling to restore content when filtering servers are unreachable, and resubmit to Chrome Web Store for security review.

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

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
SecurlyApplication
Affected:= 3.0.7

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
None
Availability
High

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

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. Verify Securly extension is installed
    Open Chrome and navigate to chrome://extensions, enable Developer mode if needed, and look for the Securly extension in the list of installed extensions.
    Affected if The Securly extension appears in the installed extensions list.
  2. Confirm the installed version is 3.0.7
    In chrome://extensions, locate the Securly extension and record the version number displayed under the extension name. Compare this to the affected version 3.0.7.
    Affected if The version shown is exactly 3.0.7.
  3. Access the extension's unpacked files
    In chrome://extensions, enable Developer mode, then click 'Pack extension' or locate the extension ID and find its installation folder in the Chrome profile directory (typically under Extensions in the user data folder).
    Affected if You are able to view the extension's source files.
  4. Check for content13.min.js file
    Browse the extension's file structure and look for a file named content13.min.js in any subdirectory.
    Affected if The file content13.min.js exists within the extension.
  5. Verify if content13.min.js is declared in manifest.json
    Open the manifest.json file in the extension root and search the content_scripts section for any reference to content13.min.js.
    Affected if content13.min.js exists but is NOT declared in the manifest.json content_scripts array, indicating dynamic registration is being used.

A user is affected if they have Securly Chrome Extension version 3.0.7 installed with the unregistered content13.min.js file present but not declared in manifest.json.

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

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Remove dynamic content script registration, declare all content scripts in manifest.json, implement proper error handling to restore content when filtering servers are unreachable, and resubmit to Chrome Web Store for security review.

Fix this in Securly Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,600
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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-2026-8879 in production — separate from our analysis above.

No notes yet

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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
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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