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Report · SecurityWeekAbout CVE-2026-51990Published

Chinese Hackers Exploit Critical Tencent Software Flaw for One-Click Code Execution

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Authoritative record:CVE-2026-51990· Critical 9.8

Not known to be exploited · CVSS 9.8 Critical.

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.
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 patch in Sogou Input Method version 16.3.0.3498 that adds validation checks for URL parameters in the protocol handler, mitigating the command-line argument injection vector. Users should ensure they have updated to this version or later via the automatic update mechanism. However, the underlying Chromium browser engine remains outdated and unpatched, so additional mitigations may be limited. No further vendor advisories indicate additional fixes or mitigations. Patch status is confirmed as fixed for the URL parameter validation issue; users should apply the update promptly.

Description

A critical vulnerability (CVE-2026-51990) in Tencent's Sogou Input Method for Windows has been exploited by the Chinese threat group UNC3569 to achieve system-level code execution via a crafted URL. The flaw involves unvalidated command-line argument injection, unrestricted URL navigation, and an outdated Chromium browser engine with disabled sandboxing. The exploit enables deployment of the GrayRabbit backdoor, which provides extensive remote control capabilities. Tencent released a patch in version 16.3.0.3498 that addresses the URL parameter validation but did not update the underlying Chromium configuration. The vulnerability has been actively exploited in the wild.

References

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