CVE-2026-8879: Version 3.0.7 of the Securly Chrome Extension dynamically registers content13.min.js as a content script via c

Routine

HIGH 7.5REMOTEDOWNGRADE

CVE-2026-8879 is a high-severity flaw (CVSS 7.5) affecting securly. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 filte

Why this priority

High severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 69%)
CISA exploited list	No
Weakness	CWE-829
Published	2026-06-03
Last modified	2026-07-22

Publisher (CNA): CERT/CC · Vendor: securly

Last updated 2026-07-22 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-03 19:16 UTCPublished CVE record published
2026-07-22 20:10 UTCUpdated Record last modified

securly securly DOWNGRADE

Affected: 3.0.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.0.7

1. Check installed version

apt-cache policy securly || rpm -q securly || securly --version

2. No fixed release: DOWNGRADE to a release before 3.0.7 (Debian / Ubuntu)

apt-cache madison securly sudo apt install securly=<VERSION_BEFORE_3.0.7> sudo apt-mark hold securly

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list securly sudo dnf downgrade securly-<VERSION_BEFORE_3.0.7> sudo dnf versionlock add securly

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-8879?

securly: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-8879 being exploited?

CVE-2026-8879 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-8879 affect?

CVE-2026-8879 affects securly. Severity is high (CVSS 7.5). 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 st

How urgent is CVE-2026-8879?

Priority 39/100. High severity; Remotely exploitable, no login, no user action

Software pages

Google Chrome vulnerabilities

Related CVEs

CVE-2026-8888 HIGH 7.5 DOWNGRADE Version 3.0.7 of the Securly Chrome Extension downloads config.json over HTTP and compiles server-provided pat
CVE-2026-8889 HIGH 7.5 DOWNGRADE Version 3.0.7 of the Securly Chrome Extension uses deprecated SHA-1 hashing for IWF CSAM URL matching (25,020
CVE-2026-8876 HIGH 7.3 DOWNGRADE Version 3.0.7 of the Securly Chrome Extension contains hardcoded, plaintext AES passphrases in securly.min.js
CVE-2026-8878 HIGH 7.5 DOWNGRADE Version 3.0.7 of the Securly Chrome Extension exposes multiple publicly accessible endpoints that allow unauth
CVE-2026-8881 HIGH 7.5 DOWNGRADE Version 3.0.7 of the Securly Chrome Extension uses EVP_BytesToKey key derivation with MD5 and a single iterati

References

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