Organization

Calif

2 mentions in 7 days · 5 in 30 days · 6 total · first seen Aug 15, 2026 · last 6d ago

Timeline6 articles

Researchers Build WeChat Zero-Click Worm Hijacking Phones via Calls

Calif researchers built WeWorm, a zero-click worm exploiting a WeChat VoIP memory-corruption RCE that Tencent has now patched.

Calif researchers found a memory corruption flaw in WeChat's VoIP stack in July using LLM-assisted analysis and built working exploits within two days, then integrated them into WeWorm, which they call the first zero-click worm spreading through WeChat calls on iOS and Android. A crafted incoming call yields remote code execution with no user interaction, giving full control of the victim's WeChat account; the attacker only needs to be on the victim's friend list, easily achieved by compromising a contact first. Tencent confirmed the bug and shipped patches in WeChat Android 8.0.77 and iOS 8.0.76, and chaining with other OS bugs could yield full device control.

Infosecurity Magazineupdated Sep 10, 00:56 UTC · 5d agofirst Sep 9, 15:00 UTC · 6d agoExploit / PoC 3 sources

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.

The Register · Securityupdated Sep 10, 00:56 UTC · 5d agofirst Sep 9, 12:45 UTC · 6d agoExploit / PoC 3 sources

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.

Security AffairsSep 8, 18:09 UTC · 7d agoExploit / PoC

“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.

Help Net SecuritySep 8, 13:40 UTC · 7d agoVulnerability

Apple macOS Screen Sharing Flaw Exploited on Internet

Actively exploited CVE-2026-65400 in macOS Screen Sharing grants pre-auth root access; attackers deploy Monero miners on exposed systems.

NCSC-NL reported active exploitation of CVE-2026-65400 (CVSS 9.8), an authentication flaw in macOS Screen Sharing patched on August 6, 2026, with root access gained and a Monero miner planted on internet-exposed systems using port 5900. Related Screen Sharing bugs CVE-2026-43779, CVE-2026-43777, and CVE-2026-43760 were fixed in macOS Tahoe 26.6, and researcher @osxreverser noted a pre-auth flaw fixed alongside them affecting roughly 40,000 exposed hosts. Calif said an AI agent produced working exploits for both pre-auth bugs in four hours, underscoring the shrinking gap between patch release and weaponization.

The Hacker NewsAug 19, 05:22 UTC · 27d agoExploit / PoC in the wildCVE-2026-65400 CVE-2026-43779 CVE-2026-43777+1 CVEs

macOS Screen Sharing Flaw Exploited to Deploy Monero Miners

Dutch NCSC confirms active exploitation of critical macOS Screen Sharing flaw CVE-2026-65400, granting root access and installing Monero miners.

CVE-2026-65400 (CVSS 9.8) is an authentication state-management flaw in macOS's built-in Screen Sharing that lets network attackers authenticate without valid credentials. The Dutch NCSC confirmed active exploitation against systems with port 5900 exposed to the internet; in every documented case attackers obtained root access and installed a Monero cryptocurrency miner. Apple patched the bug in macOS Tahoe 26.6.1, Sequoia 15.7.9, and Sonoma 14.8.9, crediting Alfredo Pesoli of Bynario. A related researcher scan found roughly 40,000 exposed Screen Sharing hosts, and security firm Calif built working exploits for related flaws in about four hours using an AI coding agent.

Security AffairsAug 15, 08:35 UTC · Aug 15, 2026Exploit / PoC in the wildCVE-2026-65400

Related CVEsby mentions

CVE-2026-654009.810%
Authentication Bypass in Apple macOS Screen Sharing
CVE-2026-65400 is a critical (CVSS 9.8) improper authentication flaw (CWE-287) in Apple macOS's Screen Sharing service, caused by an authentication state-management defect. An attacker who can reach a vulnerable Mac's Screen Sharing service over the network can authenticate without valid credentials, gaining full remote access with high impact to confidentiality, integrity, and availability. All three currently supported macOS branches are affected: Sequoia, Sonoma, and Tahoe, in versions prior to the fixed releases. The flaw is being actively exploited on the internet, with public reporting that attackers use the bypass to deploy Monero cryptominers, and CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-18. EPSS estimates a 9.9% probability of exploitation within 30 days (95th percentile).
· Apple macOS (Screen Sharing service) supported macOS releases prior to the fixed builds listed below · Apple macOS Sequoia all versions prior to 15.7.9 KEVmass
CVE-2026-437799.8<1%
A logic issue was addressed with improved restrictions.
A logic issue was addressed with improved restrictions. This issue is fixed in macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, macOS Tahoe 26.6. An app may be able to intercept network connections intended for another process.
· apple macos—
CVE-2026-437608.6<1%
An access issue was addressed with improved access restrictions.
An access issue was addressed with improved access restrictions. This issue is fixed in macOS Sonoma 14.8.8, macOS Tahoe 26.6, macOS Tahoe 26.7. An app may be able to access user-sensitive data.
· apple macos—
CVE-2026-437777.5<1%
This issue was addressed with improved input validation.
This issue was addressed with improved input validation. This issue is fixed in macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, macOS Tahoe 26.6. A remote attacker may be able to cause a denial of service.
· apple macos—

Appears with

vendor Tencent 4 product WeChat 4 product WeWorm 3 organization Bynario 2 product macOS 2 malware WeWorm 2 organization Tencent 2 vendor Apple 2 vendor Calif 2 product Screen Sharing 1 organization Georgetown University 1 organization NCSC-NL 1 malware Monero miner 1 product Weixin 1 vendor NCSC-NL 1

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