CVE-2021-42762

What it actually does

Allows a sandboxed process to abuse VFS syscalls that manipulate its filesystem namespace, tricking host processes that create UNIX sockets into treating the sandboxed process as unconfined while remaining otherwise restricted.

Why it matters to the business

Limited risk of unauthorized interaction with host services that mount sockets inside the WebKit sandbox, potentially exposing minor confidentiality or integrity issues in affected desktop or embedded web-rendering environments.

How an attack unfolds

An attacker with initial code execution inside a WebKit sandboxed process invokes VFS namespace manipulation syscalls to deceive host UNIX-socket services, enabling a narrow set of actions outside the intended sandbox boundaries.

How to fix it

Update WebKitGTK and WPE WebKit to version 2.34.1 or later; ensure dependent glib installations include commit 080ce501406be1bf821b39ed40c43aeffeb1fb2f.

How to confirm the fix worked

Confirm installed WebKitGTK/WPE WebKit packages report version 2.34.1 or newer and verify glib source contains the referenced commit hash via package manager or build logs.

Typical attack path

1. Achieve code execution inside a WebKitGTK or WPE WebKit sandboxed process
2. Invoke VFS syscalls to alter the process filesystem namespace
3. Trigger host services that create or access UNIX sockets mounted inside the sandbox
4. Perform limited operations that the host incorrectly believes originate from an unsandboxed context

How to detect it

Review system audit logs and strace-style traces for unusual VFS namespace or mount-related syscalls originating from WebKit renderer or WebProcess binaries; correlate with socket creation events on host services.

What your security team should do

• Prioritize upgrade of WebKitGTK and WPE WebKit to 2.34.1+ across all affected systems
• Audit any custom host services that expose UNIX sockets inside WebKit sandboxes
• Apply the glib commit fix in environments that build glib from source
• Review sandbox policy configurations to reduce reliance on namespace assumptions