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Report · Bleeping ComputerAbout CVE-2026-51990Published

Hackers exploit Tencent app flaw to deploy GrayRabbit malware

Source Bleeping Computer

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Authoritative record:CVE-2026-51990· Critical 9.8

Not known to be exploited · CVSS 9.8 Critical · fixed in 16.3.0.3498 : patch affected systems as a priority.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.9% chance of exploitation in 30 days – higher than 60% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 16.3.0.3498
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 16 Sep 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 29 Oct 2026.

What to do

AI-suggested

Tencent released an official fix in Sogou Input Method version 16.3.0.3498 that validates protocol handler URL arguments, restricts navigation to HTTPS, and limits allowed domains to those related to Sogou and Tencent. Users should update to this version or later to mitigate the vulnerability. Despite the patch, the embedded Chromium engine remains outdated and unsandboxed, so caution is advised. No additional vendor guidance indicates further immediate actions.

Description

A critical remote code execution vulnerability (CVE-2026-51990) in Tencent's Sogou Input Method for Windows is actively exploited by the UNC3569 threat group to deploy the GrayRabbit backdoor malware. The attack chain abuses a custom URI handler, an unrestricted URL navigation in an embedded Chromium webview, and a known flaw in an outdated Chromium 80 engine running without sandboxing. Tencent released a patch in version 16.3.0.3498 that validates URL arguments and restricts navigation to approved domains, but the underlying Chromium engine remains outdated and unsandboxed.

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