CVE-2026-42310: Pillow is a Python imaging library

Routine

MEDIUM 5.5UPGRADE

CVE-2026-42310 is a medium-severity flaw (CVSS 5.5) 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 version 4.2.0 to before version 12.2.0, an attacker can supply a malicious PDF that causes the process to hang indefinitely, consuming 100% CPU and making the application unresponsive. This issue has been patched in version 12.2.0.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 94%)
CISA exploited list	No
Weakness	CWE-835
Published	2026-05-09
Last modified	2026-07-24

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

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-09 06:16 UTCPublished CVE record published
2026-07-24 21:10 UTCUpdated Record last modified

python pillow UPGRADE

Affected: >= 4.2.0 and < 12.2.0

Fixed in: 12.2.0

Safe to downgrade to: a release before 4.2.0

1. Check installed version

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

2. UPGRADE to 12.2.0 (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 4.2.0 (Debian / Ubuntu)

apt-cache madison pillow sudo apt install pillow=<VERSION_BEFORE_4.2.0> 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_4.2.0> 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-2026-42310?

pillow: upgrade to 12.2.0. Exact commands for each OS are on this page.

Is CVE-2026-42310 being exploited?

CVE-2026-42310 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-2026-42310 affect?

CVE-2026-42310 affects pillow. Severity is medium (CVSS 5.5). Pillow is a Python imaging library. From version 4.2.0 to before version 12.2.0, an attacker can supply a malicious PDF that causes the process to hang indefinitely, consuming 100% CPU and making the application unresponsive. This issue has

How urgent is CVE-2026-42310?

Priority 21/100. No elevated risk signals yet.

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-2026-112399 HIGH 7.5 UPGRADE Pillow is a Python imaging library
CVE-2026-112398 CRITICAL 9.8 UPGRADE Pillow is a Python imaging library

References

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