Quick answers
- Is CVE-2026-59199 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-59199 being exploited in the wild.
- How severe is CVE-2026-59199?
- High severity, with a CVSS score of 7.5, published 14 July 2026.
- Which products and versions are affected?
- pillow (PyPI) < 12.3.0, ECOSYSTEM:introduced=0,fixed=12.3.0.
- Is there a fix for CVE-2026-59199?
- Yes. pillow (PyPI): upgrade to 12.3.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-59199 attacked?
- It is attacked with local access, in a software library.
- Am I affected by CVE-2026-59199?
- Check whether you run pillow (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- pillow (PyPI): upgrade to 12.3.0 or later
pip install "pillow>=12.3.0"
Technical details
A heap out-of-bounds write exists in Pillow's native C extension due to signed integer overflow in coordinate arithmetic. In `src/libImaging/Paste.c`, the `ImagingPaste()` function calculates image dimensions using signed 32-bit integers; providing coordinates near `INT_MIN` or `INT_MAX` causes these calculations to wrap around, bypassing boundary checks. In 4-byte pixel modes like RGBA, this results in a controlled backward heap underwrite via `memcpy`. The vulnerability is reachable through public APIs including `Image.paste()`, `Image.crop()`, and `Image.alpha_composite()`. The issue is fixed in version 12.3.0 by implementing checked arithmetic and wider integer types for coordinate calculations.
Affected products
- python-pillow Pillow < 12.3.0
Identifiers
- CVE-2026-59199
- GHSA-6r8x-57c9-28j4
- PYSEC-2026-3451
Timeline
- 2026-07-07: advisory: Initial GitHub Advisory published
- 2026-07-20: disclosed
- 12.3.0: patched