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.
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History

Tue, 20 Oct 2026 00:00:00 +0000

Type Values Removed Values Added
First Time appeared Python-pillow
Python-pillow pillow
Vendors & Products Python-pillow
Python-pillow pillow

Mon, 19 Oct 2026 22:15:00 +0000

Type Values Removed Values Added
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.
Title Pillow: Image.quantize() with empty palette leaks uninitialized stack memory
Weaknesses CWE-457
References
Metrics cvssV4_0

{'score': 6.9, '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'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-19T22:04:23.462Z

Reserved: 2026-10-19T20:16:09.857Z

Link: CVE-2026-112898

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-19T22:17:10.030

Modified: 2026-10-19T22:17:10.030

Link: CVE-2026-112898

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-20T01:00:09Z

Weaknesses