CVE-2026-28231: pillow_heif is a Python library for working with HEIF images and plugin for Pillow

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CRITICAL 9.1REMOTEUPGRADE

CVE-2026-28231 is a critical-severity flaw (CVSS 9.1) affecting pillow-heif. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 configu

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 47%)
CISA exploited list	No
Weakness	CWE-125, CWE-190
Published	2026-02-27
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: bigcat88

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-02-27 20:21 UTCPublished CVE record published
2026-06-17 10:28 UTCUpdated Record last modified

bigcat88 pillow-heif UPGRADE

Affected: < 1.3.0

Fixed in: 1.3.0

Safe to downgrade to: no unaffected older release

1. Check installed version

pip show pillow-heif

2. UPGRADE to 1.3.0

pip install --upgrade "pillow-heif>=1.3.0"

Exact fixes by distribution

Python (pip) · pi-heif · FIXED · 1.3.0 · vulnerable: < 1.3.0 · source

pip install --upgrade "pi-heif>=1.3.0" pip show pi-heif

Python (pip) · pillow-heif · FIXED · 1.3.0 · vulnerable: < 1.3.0 · source

pip install --upgrade "pillow-heif>=1.3.0" pip show pillow-heif

Fedora ELN · openldap · FIXED · 2.6.16-1.eln159 · FEDORA-2026-4b30c86326 · source

sudo dnf upgrade --advisory=FEDORA-2026-4b30c86326

Fedora 46 · php-pecl-yac · FIXED · 3.0.1-2.fc46 · FEDORA-2026-5f43289aa2 · source

sudo dnf upgrade --advisory=FEDORA-2026-5f43289aa2

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/bigcat88/pillow_heif/security/advisories/GHSA-5gjj-6r7v-ph3x

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-28231?

pillow-heif: upgrade to 1.3.0. Exact commands for each OS are on this page.

Is CVE-2026-28231 being exploited?

CVE-2026-28231 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-28231 affect?

CVE-2026-28231 affects pillow-heif. Severity is critical (CVSS 9.1). 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

How urgent is CVE-2026-28231?

Priority 55/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

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References

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