MSRC_CVE-2026-50257

Vulnerability from csaf_microsoft - Published: 2026-06-02 00:00 - Updated: 2026-06-11 01:40
Summary
Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in misyncdestroyfence()
Notes
Additional Resources: To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle
Disclaimer: The information provided in the Microsoft Knowledge Base is provided \"as is\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
CVE-2026-50257
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE-416 - Use After Free
Affected products
Product Identifier Version Remediation
Unresolved product id: 21316-17084 —
Product Identifier Version Remediation
Unresolved product id: 17084-1 —
Vendor Fix fix
References
To clipboard 

{
  "document": {
    "category": "csaf_vex",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Public",
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en-US",
    "notes": [
      {
        "category": "general",
        "text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
        "title": "Disclaimer"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
      "namespace": "https://msrc.microsoft.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "CVE-2026-50257 Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in misyncdestroyfence() - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-50257.json"
      },
      {
        "category": "external",
        "summary": "Microsoft Support Lifecycle",
        "url": "https://support.microsoft.com/lifecycle"
      },
      {
        "category": "external",
        "summary": "Common Vulnerability Scoring System",
        "url": "https://www.first.org/cvss"
      }
    ],
    "title": "Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in misyncdestroyfence()",
    "tracking": {
      "current_release_date": "2026-06-11T01:40:22.000Z",
      "generator": {
        "date": "2026-06-11T07:02:31.014Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2026-50257",
      "initial_release_date": "2026-06-02T00:00:00.000Z",
      "revision_history": [
        {
          "date": "2026-06-09T01:02:27.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        },
        {
          "date": "2026-06-11T01:40:22.000Z",
          "legacy_version": "2",
          "number": "2",
          "summary": "Information published."
        }
      ],
      "status": "final",
      "version": "2"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "3.0",
                "product": {
                  "name": "Azure Linux 3.0",
                  "product_id": "17084"
                }
              }
            ],
            "category": "product_name",
            "name": "Azure Linux"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "\u003cazl3 xorg-x11-server-Xwayland 0:24.1.6-4.azl3",
                "product": {
                  "name": "\u003cazl3 xorg-x11-server-Xwayland 0:24.1.6-4.azl3",
                  "product_id": "1"
                }
              },
              {
                "category": "product_version",
                "name": "azl3 xorg-x11-server-Xwayland 0:24.1.6-4.azl3",
                "product": {
                  "name": "azl3 xorg-x11-server-Xwayland 0:24.1.6-4.azl3",
                  "product_id": "21316"
                }
              }
            ],
            "category": "product_name",
            "name": "xorg-x11-server-Xwayland"
          }
        ],
        "category": "vendor",
        "name": "Microsoft"
      }
    ],
    "relationships": [
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "\u003cazl3 xorg-x11-server-Xwayland 0:24.1.6-4.azl3 as a component of Azure Linux 3.0",
          "product_id": "17084-1"
        },
        "product_reference": "1",
        "relates_to_product_reference": "17084"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "azl3 xorg-x11-server-Xwayland 0:24.1.6-4.azl3 as a component of Azure Linux 3.0",
          "product_id": "21316-17084"
        },
        "product_reference": "21316",
        "relates_to_product_reference": "17084"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-50257",
      "cwe": {
        "id": "CWE-416",
        "name": "Use After Free"
      },
      "notes": [
        {
          "category": "general",
          "text": "redhat",
          "title": "Assigning CNA"
        }
      ],
      "product_status": {
        "fixed": [
          "21316-17084"
        ],
        "known_affected": [
          "17084-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2026-50257 Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in misyncdestroyfence() - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-50257.json"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2026-06-09T01:02:27.000Z",
          "details": "0:24.1.12-1.azl3:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
          "product_ids": [
            "17084-1"
          ],
          "url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "environmentalsScore": 0.0,
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "temporalScore": 7.8,
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "products": [
            "17084-1"
          ]
        }
      ],
      "title": "Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in misyncdestroyfence()"
    }
  ]
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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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.