CVE-2026-96639
Pillow multi-frame loaders can reuse stale native image storage after mode transitions
Reported by github_m · Published October 21, 2026
Pillow is a Python imaging library. From 11.0.0 until 13.0.0, multi-frame loaders can retain an ImagingCore allocation created for a narrow frame mode while a later frame of the same dimensions changes the logical mode and decoder tiles to wider RGB or CMYK data. ImageFile.load_prepare() reuses the stale native storage because _im is non-null without verifying that its mode and size still match. Crafted PSD, MPO, DCX, or MIC frame transitions can then write wider pixels into the narrow allocation, causing native out-of-bounds writes and crashes. The MPO path can also cause a native over-read and, in demonstrated runtime-specific profiles, command execution. This issue is fixed in version 13.0.0.
Fixed versions
Upgrade to a fixed version or later. Language registries are listed first, then Linux distributions, then vendor products.
| Package | Ecosystem | Fixed in |
|---|---|---|
| nemo-gym | Chainguard | 0.5.0_rc0_git20260729-r6 |
| nemo-rl-cuda-13.0 | Chainguard | 0.7.0-r11 |
Risk scores
Affected products
| Vendor | Product | Versions |
|---|---|---|
| python-pillow | Pillow | >= 11.0.0, < 13.0.0 |
| python-pillow | Pillow | 11.0.0 |
Timeline
- Oct 17, 2026 PoC Published (4 in total, the first dated here)
- Oct 21, 2026 CVE Published
- Oct 22, 2026 EPSS Score (4 in total, the first dated here)
- Oct 22, 2026 Coalition ESS Score
- Oct 29, 2026 CVE Updated
- Oct 30, 2026 Security Advisory
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References
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-v9pv-5gc8-w2m6 x_refsource_CONFIRM
- https://github.com/python-pillow/Pillow/pull/10105 x_refsource_MISC
- https://github.com/python-pillow/Pillow/commit/78d97d994579aef81aafe123773d525f40f2522a x_refsource_MISC
- https://github.com/python-pillow/Pillow/releases/tag/13.0.0 x_refsource_MISC