Vulnerability · Published Oct 19, 2026 · Assigned by GitHub_M
CVE-2026-112898Pillow: Image.quantize() with empty palette leaks uninitialized stack memory
Medium 6.9
In plain English
A medium-severity security flaw in Pillow from python-pillow. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 28% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | pillow | no fix listed | DEBIAN-CVE-2026-112898 |
| Debian:13 | pillow | no fix listed | DEBIAN-CVE-2026-112898 |
| Debian:14 | pillow | no fix listed | DEBIAN-CVE-2026-112898 |
| PyPI | pillow | 13.0.0 | GHSA-rfgq-q3w2-pmv2 |
| Ubuntu:24.04:LTS | pillow | no fix listed | UBUNTU-CVE-2026-112898 |
| Ubuntu:26.04:LTS | pillow | no fix listed | UBUNTU-CVE-2026-112898 |
| Ubuntu:26.10 | pillow | no fix listed | UBUNTU-CVE-2026-112898 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| python-pillow | Pillow | >= 9.1.0, < 13.0.0 |
Weakness: CWE-457 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N