CVE-2020-11936

What it actually does

A flaw in gdbus permits local setgid privilege escalation by mishandling group permissions during D-Bus operations.

Why it matters to the business

Local attackers can obtain elevated group-level access on Linux systems, increasing the risk of unauthorized actions or further compromise.

How an attack unfolds

An attacker with local shell access crafts input to gdbus that triggers improper setgid handling, resulting in execution with unintended group privileges.

How to fix it

Update the GLib/D-Bus packages to a version that corrects the setgid handling in gdbus; apply vendor security updates as they become available.

How to confirm the fix worked

Confirm gdbus binary and library versions match patched releases; test local privilege boundaries with standard setgid verification tools.

Typical attack path

1. Obtain local user access on a vulnerable system
2. Invoke gdbus with specially crafted parameters
3. Trigger setgid permission mishandling
4. Execute code or commands with elevated group rights

How to detect it

Review authentication and process execution logs for unexpected gdbus invocations followed by group privilege changes; correlate with setgid binary usage.

• gdbus
• unexpected setgid transitions in auth logs

What your security team should do

• Prioritize patching GLib and related D-Bus components across all Linux fleets
• Restrict unnecessary local interactive access where possible
• Enable enhanced auditing of setgid transitions and D-Bus activity