Is CVE-2026-96638 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-96638 being exploited in the wild.

How severe is CVE-2026-96638?

Medium severity, with a CVSS score of 6.5, published 21 October 2026.

Which products and versions are affected?

pillow (PyPI) >= 9.1.0, < 13.0.0, ECOSYSTEM:introduced=9.1.0,fixed=13.0.0; Python Pillow Pillow 9.1.0 to 12.x (before 13.0.0).

Is there a fix for CVE-2026-96638?

Yes. pillow (PyPI): upgrade to 13.0.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-96638 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-96638?

Check whether you run pillow (PyPI) or Python Pillow Pillow 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.

CVE-2026-96638: Pillow BMP RLE decoder memory exhaustion

Q: Is there a fix for CVE-2026-96638?

Yes. pillow (PyPI): upgrade to 13.0.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-96638 attacked?

It is attacked over the network, in a software library.

Q: Am I affected by CVE-2026-96638?

Check whether you run pillow (PyPI) or Python Pillow Pillow 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.

CVE-2026-96638 · Severity: medium · CVSS 6.5 · Published 2026-10-21

Pillow is a Python library that processes images, including BMP format files. A crafted BMP file with specially crafted RLE compression data can trick the decoder into allocating hundreds of megabytes of memory from a small file, exhausting available memory and causing the application to crash or become unresponsive.

Technologies: pillow (PyPI), Python Pillow Pillow. Vendors: PyPI, Python Pillow.

Quick answers

Is CVE-2026-96638 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-96638 being exploited in the wild.
How severe is CVE-2026-96638?: Medium severity, with a CVSS score of 6.5, published 21 October 2026.
Which products and versions are affected?: pillow (PyPI) >= 9.1.0, < 13.0.0, ECOSYSTEM:introduced=9.1.0,fixed=13.0.0; Python Pillow Pillow 9.1.0 to 12.x (before 13.0.0).
Is there a fix for CVE-2026-96638?: Yes. pillow (PyPI): upgrade to 13.0.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-96638 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-96638?: Check whether you run pillow (PyPI) or Python Pillow Pillow 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 13.0.0 or later
```
pip install "pillow>=13.0.0"
```

Technical details

The BmpRleDecoder.decode() function in BmpImagePlugin.py lacks proper boundary checks when processing delta escapes and absolute-mode runs in RLE-compressed BMP files. An attacker can craft a malicious BMP with a large permitted width such that delta operations add approximately 255 rows per iteration without being capped against remaining destination buffer length, causing unbounded memory allocation. The fix adds a minimum-cap check to ensure appended data does not exceed dest_length.

Affected products

Python Pillow Pillow 9.1.0 to 12.x (before 13.0.0)

Identifiers

CVE-2026-96638
GHSA-24rc-8hj2-v98c

Timeline

2026-10-21: disclosed
2026-09-17: patched

References

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