{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "1.2.1"
              },
              {
                "fixed": "1.6.56"
              }
            ]
          },
          "events": [
            {
              "introduced": "f50c91b7bd6d7c539bd8820c8ab2e37a86108a44"
            },
            {
              "fixed": "d5515b5b8be3901aac04e5bd8bd5c89f287bcd33"
            }
          ],
          "repo": "https://github.com/pnggroup/libpng",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-m4pc-p4q3-4c7j"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-416"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33416.json"
  },
  "details": "LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.2.1 through 1.6.55, `png_set_tRNS` and `png_set_PLTE` each alias a heap-allocated buffer between `png_struct` and `png_info`, sharing a single allocation across two structs with independent lifetimes. The `trans_alpha` aliasing has been present since at least libpng 1.0, and the `palette` aliasing since at least 1.2.1. Both affect all prior release lines `png_set_tRNS` sets `png_ptr-\u003etrans_alpha = info_ptr-\u003etrans_alpha` (256-byte buffer) and `png_set_PLTE` sets `info_ptr-\u003epalette = png_ptr-\u003epalette` (768-byte buffer). In both cases, calling `png_free_data` (with `PNG_FREE_TRNS` or `PNG_FREE_PLTE`) frees the buffer through `info_ptr` while the corresponding `png_ptr` pointer remains dangling. Subsequent row-transform functions dereference and, in some code paths, write to the freed memory. A second call to `png_set_tRNS` or `png_set_PLTE` has the same effect, because both functions call `png_free_data` internally before reallocating the `info_ptr` buffer. Version 1.6.56 fixes the issue.",
  "id": "CVE-2026-33416",
  "modified": "2026-04-01T23:10:13.827673858Z",
  "published": "2026-03-26T16:48:54.174Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33416.json"
    },
    {
      "type": "FIX",
      "url": "https://github.com/pnggroup/libpng/commit/23019269764e35ed8458e517f1897bd3c54820eb"
    },
    {
      "type": "FIX",
      "url": "https://github.com/pnggroup/libpng/commit/7ea9eea884a2328cc7fdcb3c0c00246a50d90667"
    },
    {
      "type": "FIX",
      "url": "https://github.com/pnggroup/libpng/commit/a3a21443ed12bfa1ef46fa0d4fb2b74a0fa34a25"
    },
    {
      "type": "FIX",
      "url": "https://github.com/pnggroup/libpng/commit/c1b0318b393c90679e6fa5bc1d329fd5d5012ec1"
    },
    {
      "type": "FIX",
      "url": "https://github.com/pnggroup/libpng/pull/824"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/pnggroup/libpng/security/advisories/GHSA-m4pc-p4q3-4c7j"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33416"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "LIBPNG has use-after-free via pointer aliasing in `png_set_tRNS` and `png_set_PLTE`"
}