CVE-2026-121604

4.8 MEDIUM 0.1% exploit odds Fix listed Memory safety

What it is

wlroots before 0.20.2 contains an out-of-bounds read vulnerability in read_surface_class() in xwayland/xwm.c that allows local X11 clients to leak compositor heap memory. Attackers can set a WM_CLASS property with a NUL-terminated instance but unterminated class, exposing over-read heap bytes as the window class or app_id over IPC.

At a glance

Exploitability: Can be exploited locally on the machine with a low-privilege account. Limited direct impact.
Exploit odds: 0.1% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-11-03 16:19 UTC ReservedThe CVE id was reserved by its CNA
2026-11-03 17:18 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-11-07 04:17 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.1% in the next 30 days (EPSS).
Severity: 4.8 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-11-03 17:18 UTC
Last modified: 2026-11-07 04:17 UTC
Exploit probability: 0.1% · EPSS, next 30 days
Weakness: CWE-125 · Out-of-bounds read
Record status: Received

Attack profile CVSS 4.0 · 4.8

Attack vector: Local
Complexity: Low
Attack requirements: None
Privileges needed: Low
User interaction: None
Confidentiality: Low
Integrity: None
Availability: None

Raw vector

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-121604.md and follow it. Check whether this project is affected by CVE-2026-121604. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record