CVE-2026-28231

pillow_heif Has Integer Overflow in Encode Path Buffer Validation that Leads to Heap Out-of-Bounds Read

MEDIUM 5.5EPSS 0.7%

pillow_heif is a Python library for working with HEIF images and plugin for Pillow. Prior to version 1.3.0, an integer overflow in the encode path buffer validation of `_pillow_heif.c` allows an attacker to bypass bounds checks by providing large image dimensions, resulting in a heap out-of-bounds read. This can lead to information disclosure (server heap memory leaking into encoded images) or denial of service (process crash). No special configuration is required — this triggers under default settings. Version 1.3.0 fixes the issue.

Affected: bigcat88 · pillow_heif
CVSS v4.0 GITHUB: 5.5 MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v4.0 GitHub: 5.5 MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
CVSS v3.1 NVD: 9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
EPSS: 0.73% chance of exploitation in the next 30 days, 53rd percentile
Published: 2026-02-27
Updated: 2026-03-03

Proof-of-concept exploits (1)

advisories/GHSA-5gjj-6r7v-ph3x

CVE-2026-28231

Proof-of-concept exploits (1)

Security advisories

References