{
  "cveId": "CVE-2026-33023",
  "url": "https://patchblox.com/security/cve/CVE-2026-33023",
  "summary": "CVE-2026-33023 is fixed in libsixel on 1 platform by DEBIAN-CVE-2026-33023 (version 1:1.8.7-r2-1), released April 14, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "libsixel: libsixel is a SIXEL encoder/decoder implementation derived from kmiya\u0027s sixel",
  "description": "libsixel is a SIXEL encoder/decoder implementation derived from kmiya\u0027s sixel. In versions 1.8.7 and prior, when built with the --with-gdk-pixbuf2 option, a use-after-free vulnerability exists in load_with_gdkpixbuf() in loader.c. The cleanup path manually frees the sixel_frame_t object and its internal buffers without consulting the reference count, even though the object was created via the refcounted constructor sixel_frame_new() and exposed to the public callback. A callback that calls sixel_frame_ref(frame) to retain a logically valid reference will hold a dangling pointer after sixel_helper_load_image_file() returns, and any subsequent access to the frame or its fields triggers a use-after-free confirmed by AddressSanitizer. The root cause is a consistency failure between two cleanup strategies in the same codebase: sixel_frame_unref() is used in load_with_builtin() but raw free() is used in load_with_gdkpixbuf(). An attacker supplying a crafted image to any application built against libsixel with gdk-pixbuf2 support can trigger this reliably, potentially leading to information disclosure, memory corruption, or code execution. This issue has been fixed in version 1.8.7-r1.",
  "published": "2026-04-14T23:16:27Z",
  "severity": "high",
  "cvss": 7.8,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
  "epss": 0.00289,
  "epssPercentile": 0.21629,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "libsixel",
      "release": "Debian 14",
      "fixedVersion": "1:1.8.7-r2-1",
      "fix": "DEBIAN-CVE-2026-33023",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-33023",
      "released": "2026-04-14T23:16:27Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T19:12:23Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}