CVE-2026-50261

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Source
https://cve.org/CVERecord?id=CVE-2026-50261
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-50261.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-50261
Downstream
AZL (2)
BELL (1)
DEBIAN (1)
ECHO (1)
OESA (5)
RHSA (28)
RLSA (7)
ROOT (2)
UBUNTU (1)
Related
ALSA (7)
Published
2026-06-05T10:36:33Z
Modified
2026-10-21T10:16:45Z
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 
{
    "cna_assigner":  "redhat",
    "cwe_ids":  [
        "CWE-416"
    ],
    "osv_generated_from":  "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50261.json",
    "unresolved_ranges":  [
        {
            "extracted_events":  [
                {
                    "range":  [
                        {
                            "fixed":  "0:24.1.9-4.el10_2.2"
                        },
                        {
                            "fixed":  "0:24.1.5-6.el10_0.1"
                        },
                        {
                            "fixed":  "0:1.1.0-25.el6_10.18"
                        },
                        {
                            "fixed":  "0:1.20.4-35.el7_9"
                        },
                        {
                            "fixed":  "0:1.8.0-36.el7_9.5"
                        },
                        {
                            "fixed":  "0:21.1.3-20.el8_10.2"
                        },
                        {
                            "fixed":  "0:1.20.11-28.el8_10.2"
                        },
                        {
                            "fixed":  "0:1.15.0-10.el8_10"
                        },
                        {
                            "fixed":  "0:1.20.10-5.el8_4"
                        },
                        {
                            "fixed":  "0:1.11.0-8.el8_4.16"
                        },
                        {
                            "fixed":  "0:1.20.10-5.el8_4"
                        },
                        {
                            "fixed":  "0:1.11.0-8.el8_4.16"
                        },
                        {
                            "fixed":  "0:1.20.11-8.el8_6"
                        },
                        {
                            "fixed":  "0:21.1.3-2.el8_6.7"
                        },
                        {
                            "fixed":  "0:1.12.0-6.el8_6.18"
                        },
                        {
                            "fixed":  "0:1.20.11-8.el8_6"
                        },
                        {
                            "fixed":  "0:21.1.3-2.el8_6.7"
                        },
                        {
                            "fixed":  "0:1.12.0-6.el8_6.18"
                        },
                        {
                            "fixed":  "0:1.20.11-19.el8_8"
                        },
                        {
                            "fixed":  "0:21.1.3-13.el8_8.1"
                        },
                        {
                            "fixed":  "0:1.12.0-15.el8_8.18"
                        },
                        {
                            "fixed":  "0:1.20.11-19.el8_8"
                        },
                        {
                            "fixed":  "0:21.1.3-13.el8_8.1"
                        },
                        {
                            "fixed":  "0:1.12.0-15.el8_8.18"
                        },
                        {
                            "fixed":  "0:24.1.9-4.el9_8.2"
                        },
                        {
                            "fixed":  "0:1.20.11-34.el9_8.2"
                        },
                        {
                            "fixed":  "0:1.15.0-7.el9_8.2"
                        },
                        {
                            "fixed":  "0:1.20.11-21.el9_2"
                        },
                        {
                            "fixed":  "0:21.1.3-10.el9_2.1"
                        },
                        {
                            "fixed":  "0:1.12.0-14.el9_2.15"
                        },
                        {
                            "fixed":  "0:1.20.11-29.el9_4"
                        },
                        {
                            "fixed":  "0:22.1.9-8.el9_4.1"
                        },
                        {
                            "fixed":  "0:1.13.1-8.el9_4.10"
                        },
                        {
                            "fixed":  "0:1.20.11-34.el9_6"
                        },
                        {
                            "fixed":  "0:23.2.7-6.el9_6.1"
                        },
                        {
                            "fixed":  "0:1.14.1-11.el9_6"
                        }
                    ],
                    "source":  "AFFECTED_FIELD",
                    "strategy":  "InverseAffectedRanges"
                }
            ]
        }
    ]
}
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
Show details 
{
    "extracted_events":  [
        {
            "cpe":  "cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*",
            "range":  [
                {
                    "introduced":  "0"
                },
                {
                    "fixed":  "21.1.23"
                }
            ],
            "source":  "CPE_RANGE"
        },
        {
            "cpe":  "cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*",
            "range":  [
                {
                    "introduced":  "0"
                },
                {
                    "fixed":  "24.1.12"
                }
            ],
            "source":  "CPE_RANGE"
        },
        {
            "cpe":  "cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*",
            "range":  [
                {
                    "introduced":  "7.0"
                },
                {
                    "last_affected":  "7.0"
                }
            ],
            "source":  "CPE_STRING"
        },
        {
            "range":  [
                {
                    "fixed":  "bdd7bf57af208b1ddf57d4683d67104443b44812"
                }
            ],
            "source":  "REFERENCES_COMMIT"
        }
    ]
}

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/cve-osv-conversion/osv-output/CVE-2026-50261.json"
vanir_signatures 
[
    {
        "deprecated":  false,
        "digest":  {
            "function_hash":  "65338824587909873669415630628024203791",
            "length":  383
        },
        "id":  "CVE-2026-50261-c5408df1",
        "signature_type":  "Function",
        "signature_version":  "v1",
        "source":  "https://gitlab.freedesktop.org/xorg/xserver@bdd7bf57af208b1ddf57d4683d67104443b44812",
        "target":  {
            "file":  "Xext/sync.c",
            "function":  "SyncChangeCounter"
        }
    },
    {
        "deprecated":  false,
        "digest":  {
            "line_hashes":  [
                "250193507199759011693454702667975137262",
                "254549355503302630593844762860733065962",
                "3233652090355065373400587962311919480",
                "115426914441259299880338233375805146245",
                "166751493744464750211002044384396838693"
            ],
            "threshold":  0.9
        },
        "id":  "CVE-2026-50261-e1b6b967",
        "signature_type":  "Line",
        "signature_version":  "v1",
        "source":  "https://gitlab.freedesktop.org/xorg/xserver@bdd7bf57af208b1ddf57d4683d67104443b44812",
        "target":  {
            "file":  "Xext/sync.c"
        }
    }
]
vanir_signatures_modified 
"2026-10-21T10:16:45Z"