CVE-2026-50257

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Source
https://cve.org/CVERecord?id=CVE-2026-50257
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-50257.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-50257
Downstream
Related
Published
2026-06-05T10:31:22.052Z
Modified
2026-08-05T14:08:57.328458Z
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 misyncdestroyfence()
Details

A use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence(). A client that sets up multiple fence triggers can trigger a use-after-free function pointer call. An attacker would connect to the X server to set up a fence and await that fence, then a second X connection destroys the fence, causing the use-after-free. This may be used to crash the server, or for privilege escalation if the X server runs as root.

Database specific 
{
    "cna_assigner": "redhat",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50257.json",
    "cwe_ids": [
        "CWE-416"
    ]
}
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
f5abfb61994471023d8c6470428c8e30c411cc0b
Database specific 
{
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "21.1.23"
        },
        {
            "fixed": "24.1.12"
        },
        {
            "introduced": "7.0"
        },
        {
            "last_affected": "7.0"
        }
    ],
    "source": [
        "CPE_RANGE",
        "CPE_STRING",
        "REFERENCES"
    ],
    "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:*:*:*:*:*:*:*"
    ]
}

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

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-50257.json"
vanir_signatures_modified 
"2026-08-05T14:08:57Z"
vanir_signatures 
[
    {
        "signature_version": "v1",
        "id": "CVE-2026-50257-346119bf",
        "signature_type": "Line",
        "source": "https://gitlab.freedesktop.org/xorg/xserver@f5abfb61994471023d8c6470428c8e30c411cc0b",
        "deprecated": false,
        "digest": {
            "line_hashes": [
                "283804441557171073667499074421030927415",
                "182549721200164195479375174218594905156",
                "203003210501200808268159698036969106879",
                "310186664132389271424768665214327037518",
                "280716649147647034883147104356387738005",
                "141496341328698865648955577766256001656"
            ],
            "threshold": 0.9
        },
        "target": {
            "file": "miext/sync/misync.c"
        }
    },
    {
        "signature_version": "v1",
        "id": "CVE-2026-50257-b182fffd",
        "signature_type": "Function",
        "source": "https://gitlab.freedesktop.org/xorg/xserver@f5abfb61994471023d8c6470428c8e30c411cc0b",
        "deprecated": false,
        "digest": {
            "length": 368.0,
            "function_hash": "202232987211383363144987899258979427558"
        },
        "target": {
            "function": "FreeAwait",
            "file": "Xext/sync.c"
        }
    },
    {
        "signature_version": "v1",
        "id": "CVE-2026-50257-c53a30c0",
        "signature_type": "Line",
        "source": "https://gitlab.freedesktop.org/xorg/xserver@f5abfb61994471023d8c6470428c8e30c411cc0b",
        "deprecated": false,
        "digest": {
            "line_hashes": [
                "176267992055391940230377786184452293629",
                "123975067380831476568169779536756125924",
                "306148098665109981298698131196519568379",
                "310522931384027268965860231555596141885",
                "280716649147647034883147104356387738005",
                "241209420129595144222193617590358857211",
                "91158980354227693593649323354400958934",
                "305606590988927307651712599625726433279",
                "282539212462142276004362718184057301154",
                "138935008696749199424640175563608842263",
                "291418673052395209078296582528320578555",
                "41140863594067517935229180995085604097"
            ],
            "threshold": 0.9
        },
        "target": {
            "file": "Xext/sync.c"
        }
    },
    {
        "signature_version": "v1",
        "id": "CVE-2026-50257-ecbc8a52",
        "signature_type": "Function",
        "source": "https://gitlab.freedesktop.org/xorg/xserver@f5abfb61994471023d8c6470428c8e30c411cc0b",
        "deprecated": false,
        "digest": {
            "length": 623.0,
            "function_hash": "337022973752392151262139138040447899297"
        },
        "target": {
            "function": "FreeCounter",
            "file": "Xext/sync.c"
        }
    },
    {
        "signature_version": "v1",
        "id": "CVE-2026-50257-f207aaf3",
        "signature_type": "Function",
        "source": "https://gitlab.freedesktop.org/xorg/xserver@f5abfb61994471023d8c6470428c8e30c411cc0b",
        "deprecated": false,
        "digest": {
            "length": 448.0,
            "function_hash": "234601301309514231505303410963569289798"
        },
        "target": {
            "function": "miSyncDestroyFence",
            "file": "miext/sync/misync.c"
        }
    }
]