MediumFix available

Pillow tiled-TIFF decoder reads past tile buffer in copy4 (Unpack.c:1290)

Type: advisorySources: OSV

### Summary Pillow's libImaging `_decodeTile` decoder, used to decode tiled TIFF images, allocates a per-tile buffer using `realloc(state->buffer, TIFFTileSize(tiff))`. After each `TIFFReadTile` it then iterates `tile_y` from 0 up to `current_tile_length` and calls the configured row unpacker (here `copy4`) with the source pointer `state->buffer + tile_y * row_byte_size`. When libtiff returns a `tile_bytes_size` smaller than the worst-case `row_byte_size * tile_length`, the inner stride-and-copy loop walks past the realloc'd region and `copy4` performs a 1024-byte `memcpy` that reads up to `(tile_length-1) * row_byte_size + row_byte_size` bytes from a buffer sized only to `tile_bytes_size`. The supplied PoC TIFF triggers a 1024-byte over-read exactly 0 bytes past a 196608-byte allocation. An attacker who can convince a Pillow-using application to decode a crafted TIFF can trigger a process crash (DoS) and may cause adjacent heap memory to be copied into the decoded pixel buffer. ### Details Pillow's TIFF decoder, when libtiff reports the file is tiled, takes the `_decodeTile` path. The function: 1. Asks libtiff for `TIFFTileSize(tiff)` (the bytes-per-tile) and `TIFFTileRowSize(tiff)` (the bytes per row *as stored by libtiff*). 2. Reallocates `state->buffer` to exactly `tile_bytes_size`. 3. For each tile origin `(x, y)` and each plane, calls `TIFFReadTile` into `state->buffer`, then walks the tile row by row, calling the configured `ImagingShuffler` (here `copy4`) on each row'

Products: pillow
Affected versions: 10.0.0, 10.0.1, 10.1.0, 10.2.0, 10.3.0, 10.4.0, 11.0.0, 11.1.0, 11.2.1, 11.3.0, 12.0.0, 12.1.0, 12.1.1, 12.2.0, 12.3.0, 8.2.0, 8.3.0, 8.3.1, 8.3.2, 8.4.0, 9.0.0, 9.0.1, 9.1.0, 9.1.1, 9.2.0, 9.3.0, 9.4.0, 9.5.0
Fixed versions: 13.0.0
CVEs: CVE-2026-112395
Confirmed fixed CVEs: Not specified
Updated in this feed: 1 Nov 2026, 10:37 UTC · Revision 1

Source evidence

Pillow tiled-TIFF decoder reads past tile buffer in copy4 (Unpack.c:1290)

core-osv · Original source

Published 20 Oct 2026, 20:49 UTC

osv:GHSA-462x-pgg6-55fp

pillow

Fixed versions: 13.0.0

Complete source record

{
  "id": "72c41622dc6d61a554fd9fe50df7465ee0d0030d765485d48ecfef165a86e17e",
  "url": "https://osv.dev/vulnerability/GHSA-462x-pgg6-55fp",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Pillow tiled-TIFF decoder reads past tile buffer in copy4 (Unpack.c:1290)",
    "summary": "### Summary Pillow's libImaging `_decodeTile` decoder, used to decode tiled TIFF images, allocates a per-tile buffer using `realloc(state->buffer, TIFFTileSize(tiff))`. After each `TIFFReadTile` it then iterates `tile_y` from 0 up to `current_tile_length` and calls the configured row unpacker (here `copy4`) with the source pointer `state->buffer + tile_y * row_byte_size`. When libtiff returns a `tile_bytes_size` smaller than the worst-case `row_byte_size * tile_length`, the inner stride-and-copy loop walks past the realloc'd region and `copy4` performs a 1024-byte `memcpy` that reads up to `(tile_length-1) * row_byte_size + row_byte_size` bytes from a buffer sized only to `tile_bytes_size`. The supplied PoC TIFF triggers a 1024-byte over-read exactly 0 bytes past a 196608-byte allocation. An attacker who can convince a Pillow-using application to decode a crafted TIFF can trigger a process crash (DoS) and may cause adjacent heap memory to be copied into the decoded pixel buffer. ### Details Pillow's TIFF decoder, when libtiff reports the file is tiled, takes the `_decodeTile` path. The function: 1. Asks libtiff for `TIFFTileSize(tiff)` (the bytes-per-tile) and `TIFFTileRowSize(tiff)` (the bytes per row *as stored by libtiff*). 2. Reallocates `state->buffer` to exactly `tile_bytes_size`. 3. For each tile origin `(x, y)` and each plane, calls `TIFFReadTile` into `state->buffer`, then walks the tile row by row, calling the configured `ImagingShuffler` (here `copy4`) on each row'",
    "evidence": "osv:GHSA-462x-pgg6-55fp",
    "products": [
      {
        "name": {
          "value": "pillow",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "13.0.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "10.0.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "10.0.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "10.1.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "10.2.0",
            "evidence": "/affected/0/versions"
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          {
            "value": "10.3.0",
            "evidence": "/affected/0/versions"
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          {
            "value": "10.4.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "11.0.0",
            "evidence": "/affected/0/versions"
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          {
            "value": "11.1.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "11.2.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "11.3.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "12.0.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "12.1.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "12.1.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "12.2.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "12.3.0",
            "evidence": "/affected/0/versions"
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          {
            "value": "8.2.0",
            "evidence": "/affected/0/versions"
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          {
            "value": "8.3.0",
            "evidence": "/affected/0/versions"
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          {
            "value": "8.3.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "8.3.2",
            "evidence": "/affected/0/versions"
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          {
            "value": "8.4.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "9.0.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "9.0.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "9.1.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "9.1.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "9.2.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "9.3.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "9.4.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "9.5.0",
            "evidence": "/affected/0/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-462x-pgg6-55fp",
      "aliases": [
        "BIT-pillow-2026-112395",
        "CVE-2026-112395",
        "GHSA-462x-pgg6-55fp"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "8.2.0"
                },
                {
                  "fixed": "13.0.0"
                }
              ]
            }
          ],
          "package": {
            "name": "pillow",
            "purl": "pkg:pypi/pillow",
            "ecosystem": "PyPI"
          },
          "versions": [
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            "9.2.0",
            "9.3.0",
            "9.4.0",
            "9.5.0"
          ],
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-462x-pgg6-55fp/GHSA-462x-pgg6-55fp.json"
          }
        }
      ],
      "modified": "2026-10-26T08:56:01.770928143Z",
      "provider": "osv",
      "references": [
        "https://github.com/python-pillow/Pillow/security/advisories/GHSA-462x-pgg6-55fp",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-112395",
        "https://github.com/python-pillow/Pillow/commit/76869efdbbf2ad7dccd7536520fb61b7a00ab61e",
        "https://github.com/python-pillow/Pillow",
        "https://github.com/python-pillow/Pillow/releases/tag/13.0.0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-122"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-19T21:17:07Z",
        "github_reviewed_at": "2026-10-20T20:49:26Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-112395",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 446808,
  "published_at": "2026-10-20T20:49:26+00:00"
}