CVE-2021-28026: jpeg-xl v0.3.2 is affected by a heap buffer overflow in /lib/jxl/coeff_order.cc ReadPermutation

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HIGH 7.8DOWNGRADE

CVE-2021-28026 is a high-severity flaw (CVSS 7.8) affecting jpeg-xl. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

jpeg-xl v0.3.2 is affected by a heap buffer overflow in /lib/jxl/coeff_order.cc ReadPermutation. When decoding a malicous jxl file using djxl, an attacker can trigger arbitrary code execution or a denial of service.

Why this priority

High severity
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.2% (top 33%)
CISA exploited list	No
Weakness	CWE-787
Published	2021-03-05
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: jpeg

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

Am I affected?

Timeline

2021-03-05 14:15 UTCPublished CVE record published
2026-06-17 03:45 UTCUpdated Record last modified

jpeg jpeg-xl DOWNGRADE

Affected: 0.3.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.3.2

1. Check installed version

apt-cache policy jpeg-xl || rpm -q jpeg-xl || jpeg-xl --version

2. No fixed release: DOWNGRADE to a release before 0.3.2 (Debian / Ubuntu)

apt-cache madison jpeg-xl sudo apt install jpeg-xl=<VERSION_BEFORE_0.3.2> sudo apt-mark hold jpeg-xl

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list jpeg-xl sudo dnf downgrade jpeg-xl-<VERSION_BEFORE_0.3.2> sudo dnf versionlock add jpeg-xl

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-2021-28026?

jpeg-xl: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-28026 being exploited?

CVE-2021-28026 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-2021-28026 affect?

CVE-2021-28026 affects jpeg-xl. Severity is high (CVSS 7.8). jpeg-xl v0.3.2 is affected by a heap buffer overflow in /lib/jxl/coeff_order.cc ReadPermutation. When decoding a malicous jxl file using djxl, an attacker can trigger arbitrary code execution or a denial of service.

How urgent is CVE-2021-28026?

Priority 49/100. High severity; Public exploit reference

References

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