CVE-2026-50257: Use After Free in Red Hat Red Hat Enterprise Linux 10
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.
AI Analysis
Technical Summary
This vulnerability involves a use-after-free flaw in the X.Org X server and Xwayland within the miSyncDestroyFence() function. A client that sets up multiple fence triggers can cause a use-after-free function pointer call by connecting twice to the X server: one connection sets up and waits on a fence, while the second destroys it. This flaw may be exploited to crash the X server or escalate privileges if the server runs as root. The issue affects Red Hat Enterprise Linux 10. The CVSS 3.1 score is 7.8, indicating high severity. The vendor advisory does not currently specify a patch or remediation status.
Potential Impact
Successful exploitation can cause denial of service by crashing the X server or enable privilege escalation if the X server process runs with root privileges. This could allow an attacker with local access to gain elevated rights on the affected system. There are no known exploits in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-50257 for current remediation guidance. Until an official fix is available, restrict local access to trusted users only and consider running the X server with least privilege possible to reduce impact.
CVE-2026-50257: Use After Free in Red Hat Red Hat Enterprise Linux 10
Description
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 v3.1
Score 7.8high
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves a use-after-free flaw in the X.Org X server and Xwayland within the miSyncDestroyFence() function. A client that sets up multiple fence triggers can cause a use-after-free function pointer call by connecting twice to the X server: one connection sets up and waits on a fence, while the second destroys it. This flaw may be exploited to crash the X server or escalate privileges if the server runs as root. The issue affects Red Hat Enterprise Linux 10. The CVSS 3.1 score is 7.8, indicating high severity. The vendor advisory does not currently specify a patch or remediation status.
Potential Impact
Successful exploitation can cause denial of service by crashing the X server or enable privilege escalation if the X server process runs with root privileges. This could allow an attacker with local access to gain elevated rights on the affected system. There are no known exploits in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-50257 for current remediation guidance. Until an official fix is available, restrict local access to trusted users only and consider running the X server with least privilege possible to reduce impact.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- redhat
- Date Reserved
- 2026-06-04T14:55:24.011Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://access.redhat.com/security/cve/CVE-2026-50257","vendor":"Red Hat"}]
Threat ID: 6a22b798e29bf47b506379e4
Added to database: 6/5/2026, 11:48:40 AM
Last enriched: 6/5/2026, 12:03:53 PM
Last updated: 6/6/2026, 5:00:19 AM
Views: 4
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