{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "cpe": "cpe:2.3:a:saitoha:libsixel:*:*:*:*:*:*:*:*",
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.8.7-r1"
              }
            ],
            "source": [
              "CPE_RANGE",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6d628cf43548e1f2739cbb13afcc6e8257868db5"
            }
          ],
          "repo": "https://github.com/saitoha/libsixel",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-w46f-jr9f-rgvp"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-416"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33018.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "fixed": "1.8.7-rc1"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain a Use-After-Free vulnerability via the load_gif() function in fromgif.c, where a single sixel_frame_t object is reused across all frames of an animated GIF and gif_init_frame() unconditionally frees and reallocates frame-\u003epixels between frames without consulting the object's reference count. Because the public API explicitly provides sixel_frame_ref() to retain a frame and sixel_frame_get_pixels() to access the raw pixel buffer, a callback following this documented usage pattern will hold a dangling pointer after the second frame is decoded, resulting in a heap use-after-free confirmed by ASAN. Any application using sixel_helper_load_image_file() with a multi-frame callback to process user-supplied animated GIFs is affected, with a reliable crash as the minimum impact and potential for code execution. This issue has been fixed in version 1.8.7-r1.",
  "id": "CVE-2026-33018",
  "modified": "2026-07-08T05:36:25.102870030Z",
  "published": "2026-04-14T21:45:42.261Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33018.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/saitoha/libsixel/security/advisories/GHSA-w46f-jr9f-rgvp"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33018"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "libsixel: Use-After-Free in load_gif()"
}