{
  "cveId": "CVE-2026-33021",
  "url": "https://patchblox.com/security/cve/CVE-2026-33021",
  "summary": "CVE-2026-33021 is fixed in libsixel on 1 platform by DEBIAN-CVE-2026-33021 (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. Versions 1.8.7 and prior contain a use-after-free vulnerability in sixel_encoder_encode_bytes() because sixel_frame_init() stores the caller-owned pixel buffer pointer directly in frame-\u003Epixels without making a defensive copy. When a resize operation is triggered, sixel_frame_convert_to_rgb888() unconditionally frees this caller-owned buffer and replaces it with a new internal allocation, leaving the caller with a dangling pointer. Any subsequent access to the original buffer by the caller constitutes a use-after-free, confirmed by AddressSanitizer. An attacker who controls incoming frames can trigger this bug repeatedly and predictably, resulting in a reliable crash with potential for code execution. This issue has been fixed in version 1.8.7-r1.",
  "published": "2026-04-14T23:16:27Z",
  "severity": "high",
  "cvss": 7.3,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H",
  "epss": 0.00247,
  "epssPercentile": 0.16105,
  "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-2026-33021",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-33021",
      "released": "2026-04-14T23:16:27Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T07:25:28Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}