What’s Vulnerable › Vulnerabilities

CVE-2026-40192: Pillow is vulnerable to a FITS GZIP decompression bomb

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-15 · updated 2026-10-26
• Weakness: CWE-400

Description

Pillow is a Python imaging library. Versions 10.3.0 through 12.1.1 did not limit the amount of GZIP-compressed data read when decoding a FITS image, making them 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). If users are unable to immediately upgrade, they should only open specific image formats, excluding FITS, as a workaround.

Affected products

• python-pillow Pillow: from 10.3.0 before 12.2.0 — fixed in 12.2.0

How to fix

Upgrade to a fixed version: python-pillow Pillow 12.2.0. Check the vendor advisory for mitigations.

References

• https://github.com/python-pillow/Pillow/commit/3cb854e8b2bab43f40e342e665f9340d861aa628
• https://github.com/python-pillow/Pillow/pull/9521
• https://github.com/python-pillow/Pillow/security/advisories/GHSA-whj4-6x5x-4v2j
• https://pillow.readthedocs.io/en/stable/releasenotes/12.2.0.html#prevent-fits-decompression-bomb
• https://access.redhat.com/errata/RHSA-2026:16008
• https://access.redhat.com/errata/RHSA-2026:16009
• https://access.redhat.com/errata/RHSA-2026:16030
• https://access.redhat.com/errata/RHSA-2026:16174
• https://access.redhat.com/errata/RHSA-2026:17609
• https://access.redhat.com/errata/RHSA-2026:17611
• https://access.redhat.com/errata/RHSA-2026:19375
• https://access.redhat.com/errata/RHSA-2026:19712

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