# CVE-2026-55379: Pillow decompression bomb protection bypass in BdfFontFile

Source: https://junglewise.ai/threats/cve-2026-55379-pillow-decompression-bomb-protection-bypass-in-bdffontfile  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-06. Updated: 2026-07-20  
License: CC BY 4.0 with a link back

CVE-2026-55379 · Severity: high · CVSS 7.5 · Published 2026-07-06

Pillow, a popular Python image processing library, is vulnerable to a 'decompression bomb' attack when processing BDF font files. An attacker can provide a specially crafted, small font file that forces the library to allocate massive amounts of system memory. This can lead to a denial-of-service (DoS) condition where the application or server crashes or becomes unresponsive due to memory exhaustion.

Technologies: [pillow (PyPI)](https://junglewise.ai/threats/technologies/pillow). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-55379 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55379 being exploited in the wild.

**How severe is CVE-2026-55379?** High severity, with a CVSS score of 7.5, published 6 July 2026.

**Which products and versions are affected?** pillow (PyPI) < 12.3.0, ECOSYSTEM:introduced=0,fixed=12.3.0.

**Is there a fix for CVE-2026-55379?** Yes. pillow (PyPI): upgrade to 12.3.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-55379 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-55379?** Check whether you run pillow (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- pillow (PyPI): upgrade to 12.3.0 or later

  ```sh
  pip install "pillow>=12.3.0"
  ```


## Technical details

A vulnerability exists in `PIL/BdfFontFile.py` within the `bdf_char()` function. When processing a BDF font file, the library reads the `BBX` (bounding box) dimensions and passes them directly to `Image.new()` without performing the standard `_decompression_bomb_check()`. If a BDF glyph contains large dimensions but an empty `BITMAP` section, `Image.frombytes()` fails, and the fallback to `Image.new()` allocates memory on the C-heap based on the attacker-controlled dimensions. An attacker can use this to bypass `MAX_IMAGE_PIXELS` protections and cause a denial-of-service via memory exhaustion. This issue is fixed in Pillow version 12.3.0.

## Affected products

- python-pillow Pillow < 12.3.0

## Identifiers

- CVE-2026-55379
- GHSA-45hq-cxwh-f6vc
- PYSEC-2026-2255

## Timeline

- 2026-07-03: patched: Fix published in version 12.3.0
- 2026-07-06: advisory: NVD published CVE-2026-55379
- 2026-07-20: disclosed: GitHub Advisory GHSA-45hq-cxwh-f6vc published

## References

- [https://api.github.com/users/x-forwarded-sudo](https://api.github.com/users/x-forwarded-sudo)
- [https://github.com/x-forwarded-sudo](https://github.com/x-forwarded-sudo)
- [https://api.github.com/users/x-forwarded-sudo/gists%7B/gist_id%7D](https://api.github.com/users/x-forwarded-sudo/gists%7B/gist_id%7D)
- [https://api.github.com/users/x-forwarded-sudo/repos](https://api.github.com/users/x-forwarded-sudo/repos)
- [https://avatars.githubusercontent.com/u/223256873?v=4](https://avatars.githubusercontent.com/u/223256873?v=4)
- [https://api.github.com/users/x-forwarded-sudo/events%7B/privacy%7D](https://api.github.com/users/x-forwarded-sudo/events%7B/privacy%7D)

## Related threats

- [Pillow heap buffer overflow in TIFF encoder with mismatched geometry tags](https://junglewise.ai/threats/cve-2026-128067-pillow-heap-buffer-overflow-saving-tiff-with-libtiff-when-tags)
- [Pillow memory denial of service in TIFF and EXIF parsing](https://junglewise.ai/threats/cve-2026-128066-pillow-memory-dos-in-tiff-and-exif-ifd-parsing-via-overlapping)
- [Pillow libtiff encoder memory disclosure and crash via crafted TIFF tags](https://junglewise.ai/threats/cve-2026-112902-pillow-memory-disclosure-and-segfault-in-libtiff-encoder-via)
- [Pillow EPS load decompression bomb check bypass in Ghostscript scaling](https://junglewise.ai/threats/cve-2026-112899-pillow-eps-load-scale-lets-ghostscript-render-past-the)
- [Pillow heap buffer overflow in bundled libopenjp2](https://junglewise.ai/threats/pillow-bundled-libopenjp2-2-5-4-in-all-wheels-since-11-1-0-carries-osv-cd00a842)