CVE-2026-33636: LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network

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HIGH 7.6UPGRADE

CVE-2026-33636 is a high-severity flaw (CVSS 7.6) affecting libpng. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.6.36 through 1.6.55, an out-of-bounds read and write exists in libpng's ARM/AArch64 Neon-optimized palette expansion path. When expanding 8-bit paletted rows to RGB or RGBA, the Neon loop processes a final partial chunk without verifying that enough input pixels remain. Because the implementatio

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.6 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.8% (top 45%)
CISA exploited list	No
Weakness	CWE-125, CWE-787
Published	2026-03-26
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2026-03-26 17:16 UTCPublished CVE record published
2026-06-17 10:37 UTCUpdated Record last modified

libpng libpng UPGRADE

Affected: >= 1.6.36 and < 1.6.56

Fixed in: 1.6.56

Safe to downgrade to: a release before 1.6.36

1. Check installed version

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

2. UPGRADE to 1.6.56 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libpng

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 1.6.36 (Debian / Ubuntu)

apt-cache madison libpng sudo apt install libpng=<VERSION_BEFORE_1.6.36> sudo apt-mark hold libpng

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

dnf --showduplicates list libpng sudo dnf downgrade libpng-<VERSION_BEFORE_1.6.36> sudo dnf versionlock add libpng

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.

Advisories and coverage

Official advisories

AlmaLinux Errata: [ALSA-2026:28255] Moderate: libpng security update 2026-06-25

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-2026-33636?

libpng: upgrade to 1.6.56. Exact commands for each OS are on this page.

Is CVE-2026-33636 being exploited?

CVE-2026-33636 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-2026-33636 affect?

CVE-2026-33636 affects libpng. Severity is high (CVSS 7.6). LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.6.36 through 1.6.55, an out-of-bounds read and write exists in libpng's ARM/AArch64 Ne

How urgent is CVE-2026-33636?

Priority 40/100. High severity

Software pages

libpng vulnerabilities

Related CVEs

CVE-2026-34757 MEDIUM 5.1 UPGRADE MITIGATE LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network
CVE-2026-25646 HIGH 8.1 UPGRADE LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network
CVE-2026-33416 HIGH 7.5 UPGRADE LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network
CVE-2026-22801 MEDIUM 6.8 UPGRADE LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network
CVE-2026-22695 MEDIUM 6.1 UPGRADE LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network

References

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