CVE-2026-112898
Pillow: Image.quantize() with empty palette leaks uninitialized stack memory
Reported by github_m · Published October 19, 2026
Pillow is a Python imaging library. From 9.1.0 until 13.0.0, Pillow can disclose uninitialized stack memory when Image.quantize() uses an empty palette. ImagingPaletteCacheUpdate() leaves a local cache array uninitialized when the palette has zero entries, and the conversion path emits those bytes as output pixel indices. An attacker who controls the palette image can obtain stack contents from a returned PNG or GIF. This can disclose addresses and stack-canary data without an out-of-bounds access, memory corruption, or process crash. 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 |
|---|---|---|
| py3-pytorch-cuda-13.0 | Chainguard | 2.14.1-r2 |
| nemo-gym | Chainguard | 0.5.0_rc0_git20260729-r6 |
| py3-pillow | Chainguard | 13.0.0-r0 |
| apache-beam-python-3.12-sdk | Chainguard | 2.77.0-r5 |
| openstack-horizon-2025.2 | Chainguard | 25.5.2_git20260914-r12 |
| open-webui | Chainguard | 0.12.3-r6 |
| pillow | python | 13.0.0 |
Risk scores
Affected products
| Vendor | Product | Versions |
|---|---|---|
| python-pillow | Pillow | >= 9.1.0, < 13.0.0 |
| chainguard | py3-pytorch-cuda-13.0 | 0 |
| chainguard | nemo-gym | 0 |
| chainguard | py3-pillow | 0 |
| chainguard | apache-beam-python-3.12-sdk | 0 |
| chainguard | openstack-horizon-2025.2 | 0 |
| chainguard | open-webui | 0 |
| python-pillow | Pillow | 9.1.0 |
| chainguard | nemo-rl-cuda-13.0 | 0 |
| wolfi | py3-pillow | 0 |
| wolfi | open-webui | 0 |
| chainguard | superset-fips-6.1 | 0 |
| PyPI | Pillow | 9.1.0 |
Timeline
- Oct 19, 2026 CVE Published
- Oct 20, 2026 EPSS Score (7 in total, the first dated here)
- Oct 20, 2026 Coalition ESS Score
- Oct 21, 2026 CVE Updated
- Oct 30, 2026 Security Advisory
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References
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-rfgq-q3w2-pmv2 x_refsource_CONFIRM
- https://github.com/python-pillow/Pillow/commit/13943c8f857b22f073d30f0ef9b725a0d255f1a4 x_refsource_MISC
- https://github.com/python-pillow/Pillow/releases/tag/13.0.0 x_refsource_MISC
- https://nvd.nist.gov/vuln/detail/CVE-2026-112898 advisory
- https://github.com/advisories/GHSA-rfgq-q3w2-pmv2 advisory