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Vulnerability record · CVE-2026-56000 · published 8 July 2026

CVE-2026-56000: X.org x server use after free vulnerability

XX.Org · X Server

Local attackers with a X connection able to provide GLX commit to the X server xorg-server before 21.2.24 and xwayland before 24.1.13 could cause a Heap Use After Free, due to CommonMakeCurrent() pointing into potentially reallocated memory.

9.0 CVSS 4.0 Critical EPSS 0.31% · top 78.8% CWE-416 · Use after free
9.0CVSS 4.0 base score
0.31%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
2References
9 Jul 2026Last modified by NVD

Description

Local attackers with a X connection able to provide GLX commit to the X server xorg-server before 21.2.24 and xwayland before 24.1.13 could cause a Heap Use After Free, due to CommonMakeCurrent() pointing into potentially reallocated memory.

CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://gitlab.freedesktop.org/xorg/xserver/-/commit/2779affbdb4354e894f490e56f962527d6125043 Patch
https://www.openwall.com/lists/oss-security/2026/07/08/2 Mailing ListPatchThird Party Advisory

Track CVE-2026-56000 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2023-6816X.org x server out-of-bounds write vulnerabilityA flaw was found in X.Org server. Both DeviceFocusEvent and the XIQueryPointer reply contain a bit for each logical button currently down. Buttons ca…EPSS 2.1%9.8CVE-2017-12176Debian linux improper input validation vulnerabilityxorg-x11-server before 1.19.5 was missing extra length validation in ProcEstablishConnection function allowing malicious X client to cause X server t…EPSS 4.2%9.8CVE-2017-12177Debian linux integer overflow vulnerabilityxorg-x11-server before 1.19.5 was vulnerable to integer overflow in ProcDbeGetVisualInfo function allowing malicious X client to cause X server to cr…EPSS 4.4%9.8CVE-2017-12178Debian linux improper input validation vulnerabilityxorg-x11-server before 1.19.5 had wrong extra length check in ProcXIChangeHierarchy function allowing malicious X client to cause X server to crash o…EPSS 4.2%9.8CVE-2017-12179Debian linux integer overflow vulnerabilityxorg-x11-server before 1.19.5 was vulnerable to integer overflow in (S)ProcXIBarrierReleasePointer functions allowing malicious X client to cause X s…EPSS 4.4%9.8CVE-2017-12180Debian linux improper input validation vulnerabilityxorg-x11-server before 1.19.5 was missing length validation in XFree86 VidModeExtension allowing malicious X client to cause X server to crash or pos…EPSS 4.2%9.8CVE-2017-12181Debian linux improper input validation vulnerabilityxorg-x11-server before 1.19.5 was missing length validation in XFree86 DGA extension allowing malicious X client to cause X server to crash or possib…EPSS 4.2%9.8CVE-2017-12182Debian linux improper input validation vulnerabilityxorg-x11-server before 1.19.5 was missing length validation in XFree86 DRI extension allowing malicious X client to cause X server to crash or possib…EPSS 4.2%

Source: NIST National Vulnerability Database (record CVE-2026-56000), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.