CVE-2022-45142: The fix for CVE-2022-3437 included changing memcmp to be constant time and a workaround for a compiler bug by

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HIGH 7.5REMOTEDOWNGRADE

CVE-2022-45142 is a high-severity flaw (CVSS 7.5) affecting heimdal. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The fix for CVE-2022-3437 included changing memcmp to be constant time and a workaround for a compiler bug by adding "!= 0" comparisons to the result of memcmp. When these patches were backported to the heimdal-7.7.1 and heimdal-7.8.0 branches (and possibly other branches) a logic inversion sneaked in causing the validation of message integrity codes in gssapi/arcfour to be inverted.

Why this priority

High severity
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-354
Published	2023-03-06
Last modified	2026-06-17

Publisher (CNA): Red Hat, Inc. · Vendor: heimdal project

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

Am I affected?

Timeline

2023-03-06 23:15 UTCPublished CVE record published
2026-06-17 05:09 UTCUpdated Record last modified

heimdal project heimdal DOWNGRADE

Affected: 7.7.1 · 7.8.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.7.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 7.7.1 (Debian / Ubuntu)

apt-cache madison heimdal sudo apt install heimdal=<VERSION_BEFORE_7.7.1> sudo apt-mark hold heimdal

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

dnf --showduplicates list heimdal sudo dnf downgrade heimdal-<VERSION_BEFORE_7.7.1> sudo dnf versionlock add heimdal

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-2022-45142?

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

Is CVE-2022-45142 being exploited?

CVE-2022-45142 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-2022-45142 affect?

CVE-2022-45142 affects heimdal. Severity is high (CVSS 7.5). The fix for CVE-2022-3437 included changing memcmp to be constant time and a workaround for a compiler bug by adding "!= 0" comparisons to the result of memcmp. When these patches were backported to the heimdal-7.7.1 and heimdal-7.8.0 branc

How urgent is CVE-2022-45142?

Priority 42/100. High severity; Remotely exploitable, no login, no user action

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References

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