Vulnerability-Lookup

GHSA-4R2H-M6WP-GXG9

Vulnerability from github – Published: 2026-06-05 12:31 – Updated: 2026-06-05 12:31

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.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-50261"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-06-05T12:16:39Z",
    "severity": "HIGH"
  },
  "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.",
  "id": "GHSA-4r2h-m6wp-gxg9",
  "modified": "2026-06-05T12:31:46Z",
  "published": "2026-06-05T12:31:46Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-50261"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/security/cve/CVE-2026-50261"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2485386"
    },
    {
      "type": "WEB",
      "url": "https://gitlab.freedesktop.org/xorg/xserver/-/commit/bdd7bf57af208b1ddf57d4683d67104443b44812"
    },
    {
      "type": "WEB",
      "url": "https://lists.x.org/archives/xorg-announce/2026-June/003702.html"
    },
    {
      "type": "WEB",
      "url": "https://redhat.atlassian.net/browse/PSIRTSUPT-16950"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-50261 (GCVE-0-2026-50261)

Vulnerability from cvelistv5 – Published: 2026-06-05 10:36 – Updated: 2026-06-05 12:38

Title

Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in syncchangecounter()

Summary

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator (v2.0.3)

CWE

CWE-416 - Use After Free

Assigner

redhat

References

5 references

URL	Tags
https://access.redhat.com/security/cve/CVE-2026-50261	vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2485386	issue-trackingx_refsource_REDHAT
https://gitlab.freedesktop.org/xorg/xserver/-/com…
https://lists.x.org/archives/xorg-announce/2026-J…
https://redhat.atlassian.net/browse/PSIRTSUPT-16950

Impacted products

5 products

Vendor	Product	Version
Red Hat	Red Hat Enterprise Linux 10	cpe:/o:redhat:enterprise_linux:10
Red Hat	Red Hat Enterprise Linux 6	cpe:/o:redhat:enterprise_linux:6
Red Hat	Red Hat Enterprise Linux 7	cpe:/o:redhat:enterprise_linux:7
Red Hat	Red Hat Enterprise Linux 8	cpe:/o:redhat:enterprise_linux:8
Red Hat	Red Hat Enterprise Linux 9	cpe:/o:redhat:enterprise_linux:9

Date Public

2026-06-02 00:00

Credits

Upstream acknowledges Anonymous (Trend Micro Zero Day Initiative) as the original reporter.

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JSON

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                "id": "CVE-2026-50261",
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                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-05T12:38:42.608778Z",
                "version": "2.0.3"
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          "cpes": [
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            "confidentialityImpact": "HIGH",
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            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
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          "lang": "en",
          "time": "2026-06-02T00:00:00.000Z",
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      "title": "Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in syncchangecounter()",
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      },
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-4R2H-M6WP-GXG9

CVE-2026-50261 (GCVE-0-2026-50261)

Tags

Sightings

Nomenclature