CVE & CISA-KEV Catalog

CVE-2026-34001

HIGH
7.8
CVSS v3
NVD

Description

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.

CWE-825

How to fix

Remediation Available
tigervncAmazon
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.14.1-3.amzn2023.0.5
Fixed in:0:1.14.1-3.amzn2023.0.5
tigervnc-debuginfoAmazon
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.14.1-3.amzn2023.0.5
Fixed in:0:1.14.1-3.amzn2023.0.5
tigervnc-debugsourceAmazon
Fixed in:0:1.14.1-3.amzn2023.0.5
Fixed in:0:1.14.1-3.amzn2023.0.5
tigervnc-iconsAmazon
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.14.1-3.amzn2023.0.5
tigervnc-licenseAmazon
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.14.1-3.amzn2023.0.5
tigervnc-selinuxAmazon
Fixed in:0:1.14.1-3.amzn2023.0.5
tigervnc-serverAmazon
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.14.1-3.amzn2023.0.5
Fixed in:0:1.14.1-3.amzn2023.0.5
tigervnc-server-appletAmazon
Fixed in:0:1.8.0-24.amzn2.0.9
tigervnc-server-debuginfoAmazon
Fixed in:0:1.14.1-3.amzn2023.0.5
Fixed in:0:1.14.1-3.amzn2023.0.5
tigervnc-server-minimalAmazon
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.14.1-3.amzn2023.0.5
Fixed in:0:1.14.1-3.amzn2023.0.5
tigervnc-server-minimal-debuginfoAmazon
Fixed in:0:1.14.1-3.amzn2023.0.5
Fixed in:0:1.14.1-3.amzn2023.0.5
tigervnc-server-moduleAmazon
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.8.0-24.amzn2.0.9
Fixed in:0:1.14.1-3.amzn2023.0.5
Fixed in:0:1.14.1-3.amzn2023.0.5
tigervnc-server-module-debuginfoAmazon
Fixed in:0:1.14.1-3.amzn2023.0.5
Fixed in:0:1.14.1-3.amzn2023.0.5
xorg-x11-server-XdmxAmazon
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
xorg-x11-server-XephyrAmazon
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:21.1.13-5.amzn2023.0.9
Fixed in:0:21.1.13-5.amzn2023.0.9
xorg-x11-server-Xephyr-debuginfoAmazon
Fixed in:0:21.1.13-5.amzn2023.0.9
Fixed in:0:21.1.13-5.amzn2023.0.9
xorg-x11-server-XnestAmazon
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:21.1.13-5.amzn2023.0.9
Fixed in:0:21.1.13-5.amzn2023.0.9
xorg-x11-server-Xnest-debuginfoAmazon
Fixed in:0:21.1.13-5.amzn2023.0.9
Fixed in:0:21.1.13-5.amzn2023.0.9
xorg-x11-server-XorgAmazon
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:21.1.13-5.amzn2023.0.9
Fixed in:0:21.1.13-5.amzn2023.0.9
xorg-x11-server-Xorg-debuginfoAmazon
Fixed in:0:21.1.13-5.amzn2023.0.9
Fixed in:0:21.1.13-5.amzn2023.0.9
xorg-x11-server-XvfbAmazon
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:21.1.13-5.amzn2023.0.9
Fixed in:0:21.1.13-5.amzn2023.0.9
xorg-x11-server-Xvfb-debuginfoAmazon
Fixed in:0:21.1.13-5.amzn2023.0.9
Fixed in:0:21.1.13-5.amzn2023.0.9
xorg-x11-server-XwaylandAmazon
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:24.1.3-1.amzn2023.0.4
Fixed in:0:24.1.3-1.amzn2023.0.4
xorg-x11-server-Xwayland-debuginfoAmazon
Fixed in:0:24.1.3-1.amzn2023.0.4
Fixed in:0:24.1.3-1.amzn2023.0.4
xorg-x11-server-Xwayland-debugsourceAmazon
Fixed in:0:24.1.3-1.amzn2023.0.4
Fixed in:0:24.1.3-1.amzn2023.0.4
xorg-x11-server-Xwayland-develAmazon
Fixed in:0:24.1.3-1.amzn2023.0.4
Fixed in:0:24.1.3-1.amzn2023.0.4
xorg-x11-server-commonAmazon
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:21.1.13-5.amzn2023.0.9
Fixed in:0:21.1.13-5.amzn2023.0.9
xorg-x11-server-debuginfoAmazon
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:21.1.13-5.amzn2023.0.9
Fixed in:0:21.1.13-5.amzn2023.0.9
xorg-x11-server-debugsourceAmazon
Fixed in:0:21.1.13-5.amzn2023.0.9
Fixed in:0:21.1.13-5.amzn2023.0.9
xorg-x11-server-develAmazon
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:1.20.4-22.amzn2.0.11
Fixed in:0:21.1.13-5.amzn2023.0.9
Fixed in:0:21.1.13-5.amzn2023.0.9

This vulnerability affects an unusually large number of packages. The highest-confidence fixes are shown above; the full list is longer. Check the referenced advisories for complete coverage.

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal
Attack ComplexityLow
Privileges RequiredLow
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U

Exploit Intelligence

0.26%probability of exploitation in 30 days
18thpercentile

Low risk: more likely to be exploited than 18% of all known CVEs.

References

Related Vulnerabilities

Other CWE-825 vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2024-23638Medium6.560%-Fix
CVE-2026-33526High7.58.9%-Fix
CVE-2019-15691High7.24.7%-Fix
CVE-2023-48316Critical9.84.3%-Fix
CVE-2023-48315High8.83.9%-Fix
CVE-2026-45447High8.83.6%-Fix

Common questions

How do I fix CVE-2026-34001?

Published advisories record a fix for 98 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2026-34001 being actively exploited?

Not that we know of. CVE-2026-34001 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.26% is the estimated probability that it will be exploited in the next 30 days. That is higher than 18% of all scored CVEs.

How severe is CVE-2026-34001?

CVE-2026-34001 has a CVSS v3 base score of 7.8, rated important. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-34001 affect?

Published advisories record a fix for tigervnc (Amazon), tigervnc-debuginfo (Amazon), tigervnc-debugsource (Amazon), tigervnc-icons (Amazon), and 94 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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CVE-2026-34001 severity badge

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-15.