CVE-2026-50257
⚠️ highSummary
A use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence(). A client that sets up multiple fence triggers can trigger a use-after-free function pointer call. An attacker would connect to the X server to set up a fence and await that fence, then a second X connection destroys the fence, causing the use-after-free. This may be used to crash the server, or for privilege escalation if the X server runs as root.
CVSS Score
7.8
High
EPSS Score
0.0
Exploit Probability
Published Date
2026-06-05
First Seen: 2026-06-06
📊 Relative Risk Intelligence
This CVE is Moderate Risk - more severe than 69.6% of all 326,604 vulnerabilities in our database.
#99,150
Above average severity
Severity Percentile
🎯 CISA SSVC Assessment Updated: Jun 9, 2026
🔍 Exploitation Status
None
No known exploits
⚙️ Automatable
NO
Requires human interaction
💥 Technical Impact
Total
Complete system compromise possible
🏆 Discovered By
Upstream acknowledges Anonymous (Trend Micro Zero Day Initiative) as the original reporter.
SSVC data provided by
CISA
Last Modified
2026-06-08
Source
NVD 🔗
CVSS Vector 3.1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE IDs (Weakness Types)