Is CVE-2026-96637 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-96637 being exploited in the wild.

How severe is CVE-2026-96637?

High severity, with a CVSS score of 4, published 21 October 2026.

Which products and versions are affected?

pillow (PyPI) < 13.0.0, ECOSYSTEM:introduced=0,fixed=13.0.0; Python Pillow Pillow prior to 13.0.0.

Is there a fix for CVE-2026-96637?

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-2026-96637 attacked?

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

Am I affected by CVE-2026-96637?

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-2026-96637: Pillow memory exhaustion via SPIDER image mode F frame

Q: Which products and versions are affected?

pillow (PyPI) < 13.0.0, ECOSYSTEM:introduced=0,fixed=13.0.0; Python Pillow Pillow prior to 13.0.0.

Q: Is there a fix for CVE-2026-96637?

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-2026-96637 attacked?

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

Q: Am I affected by CVE-2026-96637?

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-2026-96637 · Severity: high · CVSS 4 · Published 2026-10-21

Pillow, a popular Python image processing library, contains a flaw in how it handles SPIDER-format image files. An attacker can craft a malicious image that passes initial validation with a small first frame, but then declares extremely large dimensions in a later frame, causing the application to allocate gigabytes of memory and exhaust system resources.

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

Quick answers

Is CVE-2026-96637 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-96637 being exploited in the wild.
How severe is CVE-2026-96637?: High severity, with a CVSS score of 4, published 21 October 2026.
Which products and versions are affected?: pillow (PyPI) < 13.0.0, ECOSYSTEM:introduced=0,fixed=13.0.0; Python Pillow Pillow prior to 13.0.0.
Is there a fix for CVE-2026-96637?: 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-2026-96637 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-96637?: 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 SpiderImageFile.seek() method in SpiderImagePlugin.py reparses later SPIDER stack frames and updates image dimensions without re-running the decompression bomb check. An attacker can pass a small, valid first frame through Image.open(), then use a mode F frame to declare arbitrarily large dimensions, causing allocation of approximately four bytes per declared pixel without validation.

Affected products

Python Pillow Pillow prior to 13.0.0

Identifiers

CVE-2026-96637
BIT-PILLOW-2026-96637
GHSA-g842-9rc4-69pw
PYSEC-2026-4338

Timeline

2026-10-21: disclosed
2026-09-29: patched

References

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