CVE-2026-50261

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Source
https://cve.org/CVERecord?id=CVE-2026-50261
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-50261.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-50261
Downstream
Related
Published
2026-06-05T10:36:33.418Z
Modified
2026-07-16T08:27:58.866620Z
Severity
  • 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
Summary
Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in syncchangecounter()
Details

A use-after-free flaw was found in the X.Org X server and Xwayland in SyncChangeCounter(). A client that sets up multiple SyncCounters can trigger a use-after-free when destroying those counters via a second client connection while changing those counters. This may be used to crash the server, or for privilege escalation if the X server runs as root.

Database specific 
{
    "cwe_ids": [
        "CWE-416"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50261.json",
    "cna_assigner": "redhat"
}
References

Affected packages

Git / gitlab.freedesktop.org/xorg/xserver

Affected ranges

Type
GIT
Repo
https://gitlab.freedesktop.org/xorg/xserver
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
8570e9fcec845f68f0c90caa51fd7a24764ea220
Fixed
af4b3d7250366e1a3822919e41fcf66da4966af2
Introduced
0d7ec5c7d9b451066a079fe56bcc9722341a91ff
Fixed
bdd7bf57af208b1ddf57d4683d67104443b44812
Database specific 
{
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "21.1.23"
        },
        {
            "fixed": "24.1.12"
        },
        {
            "introduced": "7.0"
        },
        {
            "last_affected": "7.0"
        }
    ],
    "cpe": [
        "cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*",
        "cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*",
        "cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*"
    ],
    "source": [
        "CPE_RANGE",
        "CPE_STRING",
        "REFERENCES"
    ]
}

Affected versions

7.*
7.0
Other
XORG-7_0
XORG-7_0_99_901
pre-xgldrop-merge
xorg-server-1_0_99_1
xorg-server-1_0_99_2
xorg-server-1_0_99_901
xorg-server-1_1_99_1
xorg-server-1_1_99_2
xorg-server-1.*
xorg-server-1.1.99.3
xorg-server-1.10.0
xorg-server-1.10.99.901
xorg-server-1.10.99.902
xorg-server-1.11.0
xorg-server-1.11.99.1
xorg-server-1.11.99.901
xorg-server-1.11.99.902
xorg-server-1.11.99.903
xorg-server-1.12.0
xorg-server-1.12.99.901
xorg-server-1.12.99.902
xorg-server-1.12.99.903
xorg-server-1.12.99.904
xorg-server-1.12.99.905
xorg-server-1.13.0
xorg-server-1.13.99.901
xorg-server-1.13.99.902
xorg-server-1.14.0
xorg-server-1.14.99.1
xorg-server-1.14.99.2
xorg-server-1.14.99.3
xorg-server-1.14.99.901
xorg-server-1.14.99.902
xorg-server-1.14.99.903
xorg-server-1.14.99.904
xorg-server-1.14.99.905
xorg-server-1.15.0
xorg-server-1.15.99.901
xorg-server-1.15.99.902
xorg-server-1.15.99.903
xorg-server-1.15.99.904
xorg-server-1.16.0
xorg-server-1.16.99.901
xorg-server-1.16.99.902
xorg-server-1.17.0
xorg-server-1.17.99.901
xorg-server-1.17.99.902
xorg-server-1.18.0
xorg-server-1.18.99.2
xorg-server-1.18.99.901
xorg-server-1.18.99.902
xorg-server-1.19.0
xorg-server-1.19.99.901
xorg-server-1.19.99.902
xorg-server-1.19.99.903
xorg-server-1.19.99.904
xorg-server-1.19.99.905
xorg-server-1.20.0
xorg-server-1.5.99.1
xorg-server-1.6.99.900
xorg-server-1.6.99.901
xorg-server-1.7.99.1
xorg-server-1.7.99.2
xorg-server-1.7.99.901
xorg-server-1.7.99.902
xorg-server-1.8.0
xorg-server-1.8.99.901
xorg-server-1.8.99.902
xorg-server-1.8.99.903
xorg-server-1.8.99.904
xorg-server-1.8.99.905
xorg-server-1.8.99.906
xorg-server-1.9.0
xorg-server-1.9.99.901
xorg-server-1.9.99.902
xorg-server-1.9.99.903
xorg-server-21.*
xorg-server-21.0.99.1
xorg-server-21.0.99.901
xorg-server-21.0.99.902
xorg-server-21.1.0
xorg-server-21.1.1
xorg-server-21.1.10
xorg-server-21.1.11
xorg-server-21.1.12
xorg-server-21.1.13
xorg-server-21.1.14
xorg-server-21.1.15
xorg-server-21.1.16
xorg-server-21.1.17
xorg-server-21.1.18
xorg-server-21.1.19
xorg-server-21.1.2
xorg-server-21.1.20
xorg-server-21.1.21
xorg-server-21.1.22
xorg-server-21.1.3
xorg-server-21.1.4
xorg-server-21.1.5
xorg-server-21.1.6
xorg-server-21.1.7
xorg-server-21.1.8
xorg-server-21.1.9
xwayland-24.*
xwayland-24.0.99.901
xwayland-24.0.99.902
xwayland-24.1.0
xwayland-24.1.1
xwayland-24.1.10
xwayland-24.1.11
xwayland-24.1.2
xwayland-24.1.3
xwayland-24.1.4
xwayland-24.1.5
xwayland-24.1.6
xwayland-24.1.7
xwayland-24.1.8
xwayland-24.1.9

Database specific

vanir_signatures 
[
    {
        "signature_type": "Function",
        "deprecated": false,
        "signature_version": "v1",
        "digest": {
            "length": 383.0,
            "function_hash": "65338824587909873669415630628024203791"
        },
        "source": "https://gitlab.freedesktop.org/xorg/xserver@bdd7bf57af208b1ddf57d4683d67104443b44812",
        "id": "CVE-2026-50261-c5408df1",
        "target": {
            "function": "SyncChangeCounter",
            "file": "Xext/sync.c"
        }
    },
    {
        "signature_type": "Line",
        "deprecated": false,
        "signature_version": "v1",
        "digest": {
            "line_hashes": [
                "250193507199759011693454702667975137262",
                "254549355503302630593844762860733065962",
                "3233652090355065373400587962311919480",
                "115426914441259299880338233375805146245",
                "166751493744464750211002044384396838693"
            ],
            "threshold": 0.9
        },
        "source": "https://gitlab.freedesktop.org/xorg/xserver@bdd7bf57af208b1ddf57d4683d67104443b44812",
        "id": "CVE-2026-50261-e1b6b967",
        "target": {
            "file": "Xext/sync.c"
        }
    }
]
source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-50261.json"
vanir_signatures_modified 
"2026-07-16T08:27:58Z"