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

What is CVE-2026-40192?

CVE-2026-40192 is a high-severity denial of service vulnerability in Python Pillow, published on 15 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-409, CWE-770, CWE-400

Which versions are affected by CVE-2026-40192?

4 open source packages ship an affected version, including pillow. It affects 1 product.

Products include Python Pillow.

How do I fix CVE-2026-40192?

Upgrade pillow to 12.2.0 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-40192 being exploited?

There is no known exploitation of CVE-2026-40192 in the wild and no public exploit code.

Other vulnerabilities in Python Pillow

• CVE-2014-3007 Pillow command injection Critical 10.0
• CVE-2026-96639 Pillow multi-frame loaders can reuse stale native image storage after mode transitions Critical 9.8
• CVE-2022-30595 Buffer over-flow in Pillow Critical 9.8
• CVE-2021-25289 Out of bounds write in Pillow Critical 9.8
• CVE-2016-4009 Pillow Integer overflow in ImagingResampleHorizontal Critical 9.8

All Python Pillow vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-pillow-2026-40192, CLEANSTART-2026-OR44215, CLEANSTART-2026-XY80928, CLSA-2026-1776904626, CLSA-2026-1778028238, CLSA-2026-1781744117 and 19 more.