---
id: CVE-2026-28231
aliases:
  - PYSEC-2026-2248
  - GHSA-5gjj-6r7v-ph3x
  - PYSEC-2026-2258
title: >-
  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 en…
summary: >-
  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
  provid…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
vendor: pi-heif
product: pi-heif
ecosystem: pip
affected:
  - pi-heif < 1.3.0
patched:
  - pi-heif 1.3.0
published: '2026-02-27'
updated: '2026-07-13'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/PYSEC-2026-2248'
references:
  - url: 'https://github.com/bigcat88/pillow_heif/releases/tag/v1.3.0'
  - url: >-
      https://github.com/bigcat88/pillow_heif/commit/8305a15d3780c533b762578cbe987d27a2c59c7a
  - url: >-
      https://github.com/bigcat88/pillow_heif/security/advisories/GHSA-5gjj-6r7v-ph3x
tags:
  - osv
  - pip
epss: 0.00632
epssPercentile: 0.48937
ingestedAt: '2026-07-13T18:58:08.508Z'
---

## Overview

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 packages

- `pi-heif < 1.3.0`

## Remediation

Upgrade to a patched release:

- `pi-heif 1.3.0`