CVE-2026-8879
Published: 03 June 2026
Summary
CVE-2026-8879 is a high-severity Inclusion of Functionality from Untrusted Control Sphere (CWE-829) vulnerability in Securly Securly. Its CVSS base score is 7.5 (High).
Operationally, ranked at the 20.2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-34165
Vulnerability details
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…
more
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.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Limiting P2P file sharing technology reduces inclusion of functionality or resources from untrusted external control spheres.
Enforcing installation policies prevents users from including functionality obtained from untrusted control spheres.
The inventory process requires identifying and recording the origin of all components, making inclusion of functionality from untrusted control spheres easier to detect during reviews.
Requiring approval and monitoring of maintenance tools prevents inclusion and execution of functionality obtained from untrusted sources.
Unowned portable devices represent untrusted control spheres; the prohibition prevents inclusion of functionality or data from such sources.
Strategy mandates assessment of third-party components and suppliers, directly reducing inclusion of functionality from untrusted control spheres.
Procedures can mandate supply-chain vetting and restrictions on functionality obtained from untrusted third-party or external control spheres.
Requires use of trusted sources and provenance tracking, tangibly limiting inclusion of functionality from untrusted control spheres.