wlroots before 0.20.2 Out-of-Bounds Read via read_surface_class() in xwm.c
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 0.20.2
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 0.20.2.
- Exploitation?/40Exploitation: unknown (data gap). No CISA SSVC exploitation rating yet
- Exposure?/25Exposure: unknown (data gap). No advisory context yet
- Reach?/20Reach: unknown (data gap). No tracked technology or package matched
- Severity4.8/10CVSS 4.8
- No patch0/5No signal
What would change the score
- Would score about 60 if added to CISA KEV
- Would score about 55 if CISA's SSVC rates exploitation active
- Would score about 27 if advisories confirm default setups are exposed
CVE-2026-121604 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 4.8 (medium) and affects wlroots; fixed in 0.20.2.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 5/100 · provisional
- Fix
- Fixed in 0.20.2
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
wlroots, a library used to build Wayland compositors, is affected by an out-of-bounds read in its Xwayland window manager code. A local X11 client can exploit this to leak memory from the compositor's heap, which may then be exposed as a window class or app ID.
Read the original description
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.
What to do
Upgrade to a fixed version: 0.20.2.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- wlroots wlroots
fixed in 0.20.2
Evidence 7
- Patch
- Patch
- Report
- Report
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-121604
Is CVE-2026-121604 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-121604?
wlroots: before 0.20.2.Source: cve.now feed data
How do I fix CVE-2026-121604?
Upgrade to a fixed version: 0.20.2.Source: cve.now feed data