CVE-2026-59200 Pillow: Decompression Bomb DoS via PdfParser.PdfStream.decode()
Attackers can cause memory exhaustion and denial of service by submitting crafted PDF files to applications using the Pillow library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-59200?
CVE-2026-59200 is a high-severity denial of service vulnerability in Python Pillow, published on 14 Jul 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. From 5.1.0 until 12.3.0, PdfParser.PdfStream.decode() in PIL/PdfParser.py calls zlib.decompress() with bufsize set to the PDF stream Length field without bounding the decompressed output size, allowing a crafted FlateDecode PDF stream to exhaust memory from a small file. This issue is fixed in version 12.3.0.
Which versions are affected by CVE-2026-59200?
4 open source packages ship an affected version, including pillow and Pillow. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
pillow Bitnami | From 5.1.0 | 12.3.0 |
pillow PyPI | From 5.1.0 | 12.3.0 |
pillow PyPI | From 5.1.0 | 12.3.0 |
Pillow PyPI | From 5.1.0 | 12.3.0 |
Products include Python Pillow.
How do I fix CVE-2026-59200?
Upgrade pillow to 12.3.0 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-2026-59200 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-59200 exists.
Other vulnerabilities in Python Pillow
Sources
Also known as BIT-pillow-2026-59200, CLSA-2026-1787043483, DEBIAN-CVE-2026-59200, ECHO-b776-8c4a-970e, GHSA-jjj6-mw9f-p565, MINI-248w-ccvp-jr85 and 13 more.