CVE-2024-31083

What it actually does

Use-after-free in ProcRenderAddGlyphs() after AllocateGlyph() creates multiple references to the same non-refcounted glyph object, allowing memory corruption when the glyph is later freed and accessed.

Why it matters to the business

Local attackers can obtain full code execution on systems that provide graphical X11 sessions, enabling data access, persistence, or further compromise in desktop and server environments that rely on Xorg.

How an attack unfolds

An authenticated local user sends a specially crafted X protocol request that triggers repeated glyph allocation and deallocation paths inside the X server; the resulting dangling pointer is reused to corrupt memory and execute attacker-controlled code.

How to fix it

Upgrade the Xorg server packages to the corrected versions released by the distribution vendor; restart affected X sessions or reboot after installation.

How to confirm the fix worked

Confirm the installed Xorg server version matches or exceeds the vendor-supplied fixed release and run any available regression tests or static-analysis checks against the glyph allocation routines.

Typical attack path

1. Obtain a local authenticated session on a host running Xorg
2. Connect to the X server and issue a malicious RenderAddGlyphs request
3. Trigger the double-free / use-after-free condition in glyph handling
4. Leverage the resulting memory corruption for arbitrary code execution

How to detect it

Inspect system and Xorg logs for unexpected crashes or segmentation faults around glyph rendering calls; correlate with authentication events immediately preceding anomalous X protocol activity.

What your security team should do

• Apply the vendor patch for the Xorg server at the earliest maintenance window
• Limit local user access to X11 sockets where feasible
• Review and tighten X server configuration to reduce attack surface