CVE-2026-112399: Pillow is a Python imaging library

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HIGH 7.5REMOTEUPGRADE

CVE-2026-112399 is a high-severity flaw (CVSS 7.5) affecting pillow. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Pillow is a Python imaging library. From 8.1.0 until 13.0.0, Pillow can allocate an APNG disposal background at the full canvas size before applying the decompression-bomb check. A crafted APNG with a small first frame, a very large declared canvas, and background disposal or first-frame OP_PREVIOUS reaches PngImageFile._seek while Image.open() positions frame zero. The full-canvas allocation occurs inside Image.open() without requiring pixel loa

Why this priority

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

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 68%)
CISA exploited list	No
Weakness	CWE-789
Published	2026-10-19
Last modified	2026-10-27

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

Last updated 2026-10-27 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-10-19 22:17 UTCPublished CVE record published
2026-10-27 21:02 UTCUpdated Record last modified

python pillow UPGRADE

Affected: >= 8.1.0 and < 13.0.0

Fixed in: 13.0.0

Safe to downgrade to: a release before 8.1.0

1. Check installed version

apt-cache policy pillow || rpm -q pillow || pillow --version

2. UPGRADE to 13.0.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade pillow

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade pillow

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 8.1.0 (Debian / Ubuntu)

apt-cache madison pillow sudo apt install pillow=<VERSION_BEFORE_8.1.0> sudo apt-mark hold pillow

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list pillow sudo dnf downgrade pillow-<VERSION_BEFORE_8.1.0> sudo dnf versionlock add pillow

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2026-112399?

pillow: upgrade to 13.0.0. Exact commands for each OS are on this page.

Is CVE-2026-112399 being exploited?

CVE-2026-112399 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-2026-112399 affect?

CVE-2026-112399 affects pillow. Severity is high (CVSS 7.5). Pillow is a Python imaging library. From 8.1.0 until 13.0.0, Pillow can allocate an APNG disposal background at the full canvas size before applying the decompression-bomb check. A crafted APNG with a small first frame, a very large declare

How urgent is CVE-2026-112399?

Priority 44/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

Related CVEs

CVE-2026-112402 HIGH 7.5 UPGRADE Pillow is a Python imaging library
CVE-2026-112401 HIGH 7.5 UPGRADE Pillow is a Python imaging library
CVE-2026-112400 HIGH 7.5 UPGRADE Pillow is a Python imaging library
CVE-2026-112398 CRITICAL 9.8 UPGRADE Pillow is a Python imaging library
CVE-2026-112397 HIGH 7.5 UPGRADE Pillow is a Python imaging library

References

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