CVE-2026-112891 Pillow: Quadratic GIF comment copying during save
An attacker can cause excessive CPU consumption and denial of service by supplying a crafted GIF image with a large comment to applications using Pillow.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-112891?
CVE-2026-112891 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 9.2.0 until 13.0.0, Pillow performs quadratic copying when saving a GIF with a long comment. _get_global_header() repeatedly copies portions of comment data while assembling the global header, including comments retained from an untrusted input image. An attacker can supply an image with a large GIF comment to an application that saves it as GIF. This can consume excessive CPU and delay or deny service. This issue is fixed in version 13.0.0.
Weakness: CWE-407
Which versions are affected by CVE-2026-112891?
3 open source packages ship an affected version, including pillow. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
pillow Bitnami | From 9.2.0 | 13.0.0 |
pillow PyPI | From 9.2.0 | 13.0.0 |
pillow PyPI | From 9.2.0 | 13.0.0 |
Products include Python Pillow.
How do I fix CVE-2026-112891?
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-2026-112891 being exploited?
There is no known exploitation of CVE-2026-112891 in the wild and no public exploit code.
Other vulnerabilities in Python Pillow
Sources
Also known as BIT-pillow-2026-112891, DEBIAN-CVE-2026-112891, ECHO-ecd4-ef3e-e3de, GHSA-fc9g-5qg7-mf45, UBUNTU-CVE-2026-112891.