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VulnerabilityPublished

CVE-2026-123139: Opera Neon · Improper Verification of Source of a Communication Channel

Affects Opera NeonSource CVE Database V5

0
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Not known to be exploited · CVSS 5.8 Medium.

Data as of 12 Nov 2026, 12:34 UTC

CVSS 4.0 base score
5.8Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Opera)CVSS 4.05.8
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N/E:U

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 12 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
OperaNeonAffected
  • =1.0.0
Fixed in–

AI-suggested

Until a fix is available, users should avoid installing untrusted browser extensions and monitor official Opera channels for updates.

Description

CVE-2026-123139 is a medium severity vulnerability in Opera Neon 1.0.0 on macOS and Windows. It involves improper verification of the source of a communication channel, allowing a malicious browser extension to send commands through the MCP Hub to the built-in Browser Operator extension, potentially taking control of the browser.

References

Community reviews

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