WeChat Worm Can Hijack Accounts Without Victims Answering Calls
Researchers demoed WeWorm, a zero-click WeChat worm hijacking accounts via incoming VoIP calls using a memory corruption flaw; Tencent patched it in August.
Researchers at Calif exploited a memory corruption bug in WeChat's VoIP system, taking over accounts through an incoming call even if the victim never answers or touches the phone. The attacker must already be a WeChat contact, but compromising a friend's account bypasses this, and chained calls spread the worm across three Android and iOS test phones in seconds. Tencent fixed the flaw in Android 8.0.77 and iOS 8.0.76 released in August, and researchers found no evidence of real-world exploitation. WeChat and Weixin reported 1.418 billion combined monthly active users at the end of 2025.
WeChat Zero-Click Worm Took Over Accounts on iPhone and Android via Incoming Calls
Researchers demonstrated a zero-click WeChat worm that hijacked accounts via incoming calls; Tencent blocked the exploit server-side after July disclosure, no real attacks reported.
Security firm Calif built a worm that seized WeChat accounts via incoming calls without any target interaction, demonstrating it spreading across three test phones (Android to iPhone to Android). Once exploited, the attacker gains full control of the WeChat account, including messages, calls, payments, and mini programs, though not the phone itself. Tencent mitigated the flaw server-side, confirmed blocked on 28 August, shipping WeChat 8.0.77 for Android and 8.0.76 for iOS on 21 August. No CVE has been assigned, Tencent published no advisory, and no attacks in the wild have been reported; WeChat/Weixin counts 1.439 billion monthly active users.
“Zero-click” WeChat worm could hijack accounts and spread via a single call
Researchers discovered a critical memory corruption flaw in WeChat's VoIP stack enabling a zero-click worm, WeWorm, that hijacks accounts via calls; Tencent patched it.
Calif researchers weaponized a memory corruption issue in WeChat's VoIP stack into "WeWorm", a worm that spreads through WeChat calls without user interaction, hijacks each victim's account, and propagates via saved contacts across iOS and Android, potentially reaching millions of devices within hours. Exploitation takes seconds and grants full account control, and chaining with other reported Android/iOS bugs could lead to full device control. Tencent issued updated WeChat versions for iOS and Android and applied server-side mitigations; technical details remain withheld. WeChat has over a billion users, overwhelmingly in China.
WeChat worm could pwn a friend before they even answered the call
Calif researchers demoed WeWorm, a zero-click WeChat VoIP memory-corruption worm enabling account takeover; Tencent patched it August 21.
Security firm Calif found a memory corruption bug in WeChat's VoIP stack that let a trusted contact take over a user's account simply by calling them, without the call being answered. The demo worm then called the victim's contacts to self-propagate across iOS and Android; declining the call prevented infection. Tencent pushed fixes on August 21, and Calif said chaining the bug with other Android and iOS flaws could yield full device control. Calif used AI to find the vulnerability and build its first RCE exploit in about two days.