FKIE_CVE-2026-50256

Vulnerability from fkie_nvd - Published: 2026-06-05 12:16 - Updated: 2026-06-05 13:27
Severity
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. A mismatch between the X server and the libXfont2 library's maximum font name length can cause a stack buffer overflow during font alias resolution. The server allocates a 256 byte stack buffer but libXfont2's alias target name length is 1024 bytes. A font alias name between 257 and 1023 bytes causes the X server to copy that name into the undersized stack buffer without further checks. This may be used to crash the server, or for privilege escalation if the X server runs as root.
References
secalert@redhat.comhttps://access.redhat.com/security/cve/CVE-2026-50256
secalert@redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=2485380
secalert@redhat.comhttps://gitlab.freedesktop.org/xorg/xserver/-/commit/bb5158f962dc935e58ef8b4b5fcb31be201a6e07
secalert@redhat.comhttps://lists.x.org/archives/xorg-announce/2026-June/003702.html
secalert@redhat.comhttps://redhat.atlassian.net/browse/PSIRTSUPT-16950
Impacted products
Vendor Product Version
To clipboard 

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. A mismatch between the X server and the libXfont2 library\u0027s maximum font name length can cause a stack buffer overflow during font alias resolution. The server allocates a 256 byte stack buffer but libXfont2\u0027s alias target name length is 1024 bytes. A font alias name between 257 and 1023 bytes causes the X server to copy that name into the undersized stack buffer without further checks. This may be used to crash the server, or for privilege escalation if the X server runs as root."
    }
  ],
  "id": "CVE-2026-50256",
  "lastModified": "2026-06-05T13:27:38.750",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "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"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "secalert@redhat.com",
        "type": "Primary"
      }
    ]
  },
  "published": "2026-06-05T12:16:38.727",
  "references": [
    {
      "source": "secalert@redhat.com",
      "url": "https://access.redhat.com/security/cve/CVE-2026-50256"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2485380"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://gitlab.freedesktop.org/xorg/xserver/-/commit/bb5158f962dc935e58ef8b4b5fcb31be201a6e07"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://lists.x.org/archives/xorg-announce/2026-June/003702.html"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://redhat.atlassian.net/browse/PSIRTSUPT-16950"
    }
  ],
  "sourceIdentifier": "secalert@redhat.com",
  "vulnStatus": "Undergoing Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-121"
        }
      ],
      "source": "secalert@redhat.com",
      "type": "Primary"
    }
  ]
}


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