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China-Linked Hackers Exploit Chrome-Windows Zero-Day Chain to Deploy GRIMWEDGE

Volexity attributes spear-phishing campaign exploiting Chrome-Windows zero-day chain to Chinese actors UTA0560 and APT31 deploying GRIMWEDGE and LONGTALE.

Volexity attributes a September 1, 2026 spear-phishing campaign targeting NGOs to China-linked UTA0560, which abused a reflected XSS flaw on a US university website to trigger a three-part exploit chain (CVE-2026-85046, CVE-2026-87491, CVE-2026-85880) escaping the Chrome V8 and browser sandboxes to deploy the GRIMWEDGE JavaScript backdoor with reconnaissance, file management, and command execution capabilities. The same chain was used near-simultaneously by JungleBamboo (APT31) to deploy SUPERSTOMP, installing the LONGTALE/GemStone credential-stealing Chrome extension masquerading as Google Gemini. The Chrome flaws were patched in Chromium but not yet in stable Chrome, creating an unusual patch-gap zero-day window attackers raced to exploit.

The Hacker Newsupdated · 4h agofirst · 1d agoThreat actor in the wild 17 sourcesCVE-2026-85046CVE-2026-87491CVE-2026-858801· 1 read

Multiple Chinese hacking groups seen using identical Chrome zero-day exploit

Four China-linked espionage groups share identical BlueMoon Chrome zero-day exploit kit targeting US defense contractors and Asian government agencies.

Proofpoint identified at least four Chinese-aligned espionage groups (TA412/RedBravo, UNK_LateNight, UNK_DoubleCheck, UNK_QuietRacket) using an identical Chrome zero-day exploit kit dubbed BlueMoon in late August through this week. Targets include US defense contractors, NGOs, mining companies, and Southeast Asian government agencies. The exploit chains a Chromium patch-gap vulnerability with a Windows flaw, delivering malware such as ShadowPad and a fake Gemini browser extension backdoor, with possible AI-assisted exploit development.

The Record · 7d agoExploit / PoC in the wild 2 sources1