CVE-2026-112401 Pillow: Quadratic GIF comment concatenation allows DoS in Image.open()
Attackers can cause excessive CPU consumption and denial of service by submitting crafted GIF 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-2026-112401?
CVE-2026-112401 is a medium-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 5.4.0 until 13.0.0, Pillow performs quadratic copying while parsing GIF comments. GifImageFile._seek() repeatedly appends immutable bytes for comment sub-blocks and multiple comment extensions, and frame zero is parsed during Image.open(). An attacker can submit a small-dimension GIF containing many comment extensions to any application that opens the file. This can consume excessive CPU and deny service before the application can inspect the image. This issue is fixed in version 13.0.0.
Weakness: CWE-407
Which versions are affected by CVE-2026-112401?
3 open source packages ship an affected version, including pillow and Pillow. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
pillow Bitnami | From 5.4.0 | 13.0.0 |
pillow PyPI | From 5.4.0 | 13.0.0 |
Pillow PyPI | From 5.4.0 | 13.0.0 |
Products include Python Pillow.
How do I fix CVE-2026-112401?
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-2026-112401 being exploited?
There is no known exploitation of CVE-2026-112401 in the wild and no public exploit code.
Other vulnerabilities in Python Pillow
Sources
Also known as BIT-pillow-2026-112401, DEBIAN-CVE-2026-112401, ECHO-c6b8-6481-18c0, GHSA-74r2-7ff9-mjj2, UBUNTU-CVE-2026-112401.