CVE-2026-56000: x.org x_server Use After Free
CVSS: 9.0v4.0CriticalAnalyzed
AliasesUBUNTU-CVE-2026-56000DEBIAN-CVE-2026-56000CGA-5qwg-f4pf-rhfxCGA-gf43-rr9j-22vr
Published 08-07-2026Last modified 08-07-2026
Vulnerability summary
CVE-2026-56000 is a critical (CVSS 9.0) Use After Free vulnerability in x.org x_server. EPSS estimates a 0.31% chance of exploitation in the next 30 days, higher than 22.2% of scored vulnerabilities.
CVSS score
9.0/10
010
Critical · v4.0 (CVE.org)EPSS score
0.31%
0%100%
Low · +0.09 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 16 · Related 11MGASA-2026-0303OPENSUSE-SU-2026:11227-1OPENSUSE-SU-2026:11244-1OPENSUSE-SU-2026:21273-1OPENSUSE-SU-2026:21283-1RHSA-2026:38489RHSA-2026:38490RHSA-2026:50100RHSA-2026:50718RHSA-2026:52398SUSE-SU-2026:22617-1SUSE-SU-2026:2786-1SUSE-SU-2026:2787-1SUSE-SU-2026:2788-1SUSE-SU-2026:2789-1SUSE-SU-2026:2791-1CGA-6CMX-33GR-3PWJ
Timeline
- 08-07-2026PublishedVulnerability first disclosed.
- 08-07-2026Last modifiedVulnerability information updated.
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 metrics
8 scores · 6 sources · 2 versionsCritical 9.0Preferred score · CVE.org (CNA)
CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:HSourcesAll 5 agree
- OSV · UbuntuEcosystem advisory · calculated9.0CriticalCVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- OSV · WolfiEcosystem advisory · calculated9.0CriticalCVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- OSV · ChainguardEcosystem advisory · calculated9.0CriticalCVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- NVDNIST9.0CriticalCVSS: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:X/V:X/RE:X/U:X
High 7.8Preferred score · OSV · Ubuntu (Ecosystem advisory) · calculated from vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HSourcesAll 3 agree
- OSV · DebianEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- NVDNIST7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.31%
Chance of exploitation in the next 30 days
Percentile
22%
Versus all other CVEs
30-day change
+0.09 pp
From 0.22% on 20-09-2026
20-09-202620-10-2026
EPSS score0.31%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu4 products
- xorg-serverAll versions (No fix recorded)
- xorg-server-hwe-16.04All versions (No fix recorded)
- xorg-server-hwe-18.04All versions (No fix recorded)
- xwaylandAll versions (No fix recorded)
X.org3 products
- x_server< 21.2.24
- xorg-x11-server< 21.1.24
- xwayland< 24.1.13
Debian2 products
- xorg-serverAll versions (No fix recorded) | < 2:21.1.16-1.3+deb13u4 | < 2:21.1.24-1
- xwaylandAll versions (No fix recorded) | < 2:24.1.13-1
Chainguard1 product
- xorg-server< 21.1.24-r0
Wolfi1 product
- xorg-server< 21.1.24-r0
5 vendors · 11 products
References
8 links- www.openwall.com/lists/oss-security/2026/07/08/2Vendor AdvisoryREPORTAdvisoryMailing ListPatchThird Party Advisory
