CVE-2026-112406 Pillow: Infinite loop in PdfParser.rewrite_pages on page tree Parent cycle
An attacker can cause a denial of service by supplying a cyclic PDF to applications using Pillow, leading to an infinite loop and high CPU usage.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-112406?
CVE-2026-112406 is a high-severity denial of service vulnerability in Python Pillow, published on 19 Oct 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 13.0.0, Pillow can enter an infinite loop while rewriting PDF pages. PdfParser.rewrite_pages() follows Parent relationships without detecting a cycle in the page tree. An attacker can supply a cyclic PDF to an application that appends an image to that PDF. This can hold the worker at full CPU and deny service. This issue is fixed in version 13.0.0.
Weakness: CWE-835
Which versions are affected by CVE-2026-112406?
3 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 | 13.0.0 |
pillow PyPI | From 5.1.0 | 13.0.0 |
Pillow PyPI | From 5.1.0 | 13.0.0 |
Products include Python Pillow.
How do I fix CVE-2026-112406?
Upgrade pillow to 13.0.0 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-2026-112406 being exploited?
There is no known exploitation of CVE-2026-112406 in the wild and no public exploit code.
Other vulnerabilities in Python Pillow
Sources
Also known as BIT-pillow-2026-112406, DEBIAN-CVE-2026-112406, ECHO-6350-5938-a46a, GHSA-f2g6-542v-9j58, ROOT-APP-PYPI-CVE-2026-112406, UBUNTU-CVE-2026-112406.