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BIT-pillow-2026-55379 — Pillow BdfFontFile`: `Image.new()` called without `_decompression_bomb_check()` — bomb protection bypass via font loadi…

2026-10-02T05:13:22.051866+00:00

Affected: Bitnami: pillow

Pillow is a Python imaging library. Prior to 12.3.0, PIL/BdfFontFile.py bdf_char() read the BBX width and height field from a BDF font file and passed attacker-controlled dimensions to Image.new() without calling Image._decompression_bomb_check(), bypassing Pillow's documented decompression bomb protection and allowing excessive memory allocation. This issue is fixed in version 12.3.0.

CVE-2026-55379 — Pillow BdfFontFile`: `Image.new()` called without `_decompression_bomb_check()` — bomb protection bypass via font loadi…

2026-10-02T05:13:22.051981+00:00

Affected: python-pillow Pillow

GHSA-45hq-cxwh-f6vc — Pillow `BdfFontFile`: `Image.new()` called without `_decompression_bomb_check()` — bomb protection bypass via font load…

2026-10-02T05:13:22.052048+00:00

Affected: PyPI: pillow

### Summary `PIL/BdfFontFile.py` `bdf_char()` (lines 84–88) reads the `BBX width height` field from a BDF font file and passes the dimensions directly to `Image.new()` without calling `Image._decompression_bomb_check()`. This completely bypasses Pillow's documented decompression bomb protection.

`Image.open()` enforces `MAX_IMAGE_PIXELS = 89,478,485` and raises `DecompressionBombError` for images exceeding `2 × MAX = 178,956,970` pixels. The BDF font loading path calls `Image.new()` directly, which only calls `_check_size()` (validates `>= 0`) — no pixel count limit.

**Vulnerable code (`PIL/BdfFontFile.py` lines 84–88):** ```python # width, height from attacker-controlled "BBX width height x y" line try: im = Image.frombytes("1", (width, height), bitmap, "hex", "1") except ValueError: # TRIGGERED when BITMAP section is empty (zero hex lines) im = Image.new("1", (width, height)) # ← NO _decompression_bomb_check()! # ^ This image is stored in self.glyph[ch] — persists in memory ```

**Attack trigger:** A BDF glyph with `BBX 20000 20000` and an empty `BITMAP` section causes `Image.frombytes()` to raise `ValueError`, then `Image.new("1", (20000, 20000))` allocates **50 MB** of C-heap silently. Image.open() would raise `DecompressionBombError` for the same dimensions.

## Steps to reproduce

**Minimal malicious BDF file (270 bytes):** ``` STARTFONT 2.1 SIZE 16 75 75 FONTBOUNDINGBOX 16 16 0 -4 STARTPROPERTIES 1 COMMENT placeholder ENDPROPERTIES CHARS 1 STARTCHA…

PYSEC-2026-2255

2026-10-02T05:13:22.052159+00:00

Affected: PyPI: pillow