GHSA-whj4-6x5x-4v2j

FITS GZIP decompression bomb in Pillow

Source: GitHub Advisory Database (reviewed) High CVE-2026-40192

Packages

Ecosystem	Package	Affected	Fixed in
PyPI	pillow	>= 10.3.0, < 12.2.0	12.2.0

Details

As written in the advisory (Markdown source, shown as plain text).

### Impact Pillow did not limit the amount of GZIP-compressed data read when decoding a FITS image, making it vulnerable to decompression bomb attacks. A specially crafted FITS file could cause unbounded memory consumption, leading to denial of service (OOM crash or severe performance degradation). ### Patches The amount of data read is now limited to the necessary amount. Fixed in Pillow 12.2.0 (PR #9521). ### Workarounds Avoid Pillow >= 10.3.0, < 12.2.0 Only open [specific image formats](https://pillow.readthedocs.io/en/stable/releasenotes/8.0.0.html#image-open-add-formats-parameter), excluding FITS.

References

External links from the advisory. They lead to third-party sites.

https://github.com/python-pillow/Pillow/security/advisories/GHSA-whj4-6x5x-4v2j web
https://nvd.nist.gov/vuln/detail/CVE-2026-40192 advisory
https://github.com/python-pillow/Pillow/pull/9521 web
https://github.com/python-pillow/Pillow/commit/3cb854e8b2bab43f40e342e665f9340d861aa628 web
https://github.com/python-pillow/Pillow package
https://pillow.readthedocs.io/en/stable/releasenotes/12.2.0.html#prevent-fits-decompression-bomb web