X.org X Server miSyncTriggerFence expired pointer dereference

CVSS Meta Temp Score
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CTI Interest Score
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7.8$0-$5k0.00

Summaryinfo

A vulnerability was found in X.org X Server. It has been rated as critical. Affected is the function miSyncTriggerFence. This manipulation causes expired pointer dereference. The identification of this vulnerability is CVE-2026-34001. The attack can only be executed locally. There is no exploit available.

Detailsinfo

A vulnerability has been found in X.org X Server (version unknown) and classified as critical. Affected by this vulnerability is the function miSyncTriggerFence. The manipulation with an unknown input leads to a expired pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-825. The product dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

A flaw was found in the X.Org X server. This use-after-free vulnerability occurs in the XSYNC fence triggering logic, specifically within the miSyncTriggerFence() function. An attacker with access to the X11 server can exploit this without user interaction, leading to a server crash and potentially enabling memory corruption. This could result in a denial of service or further compromise of the system.

The advisory is shared at access.redhat.com. This vulnerability is known as CVE-2026-34001 since 03/25/2026. The exploitation appears to be easy. An attack has to be approached locally. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 05/01/2026).

The vulnerability scanner Nessus provides a plugin with the ID 310423 (Fedora 42 : tigervnc (2026-0b633ecc7c)), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at Tenable (310423), EUVD (EUVD-2026-25230) and CERT Bund (WID-SEC-2026-1119). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Fedora Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • IGEL OS
  • OpenBSD OpenBSD
  • Open Source X.Org X11
  • Open Source Xwayland

Productinfo

Vendor

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.8
VulDB Meta Temp Score: 7.8

VulDB Base Score: 7.8
VulDB Temp Score: 7.8
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.8
CNA Vector (redhat): 🔒

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Expired pointer dereference
CWE: CWE-825
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 310423
Nessus Name: Fedora 42 : tigervnc (2026-0b633ecc7c)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

03/25/2026 CVE reserved
04/23/2026 +28 days Advisory disclosed
04/23/2026 +0 days VulDB entry created
05/01/2026 +8 days VulDB entry last update

Sourcesinfo

Vendor: x.org

Advisory: access.redhat.com
Status: Confirmed

CVE: CVE-2026-34001 (🔒)
GCVE (CVE): GCVE-0-2026-34001
GCVE (VulDB): GCVE-100-359149
EUVD: 🔒
CERT Bund: WID-SEC-2026-1119 - X.Org X11, Xwayland: Mehrere Schwachstellen

Entryinfo

Created: 04/23/2026 18:13
Updated: 05/01/2026 22:51
Changes: 04/23/2026 18:13 (60), 04/23/2026 19:29 (1), 04/27/2026 22:39 (2), 04/28/2026 14:32 (7), 05/01/2026 22:51 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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