CVE-2006-5989: Off-by-one error in the der_get_oid function in mod_auth_kerb 5.0 allows remote attackers to cause a denial of

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MEDIUM 5.0DOWNGRADE

CVE-2006-5989 is a medium-severity flaw (CVSS 5.0) affecting mod auth kerb. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Off-by-one error in the der_get_oid function in mod_auth_kerb 5.0 allows remote attackers to cause a denial of service (crash) via a crafted Kerberos message that triggers a heap-based buffer overflow in the component array.

Why this priority

EPSS top 10%: very likely to be exploited

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

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	4.0% (top 10%)
CISA exploited list	No
Published	2006-11-20
Last modified	2026-06-16

Publisher (CNA): Red Hat, Inc. · Vendor: mod auth kerb

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2006-11-20 21:07 UTCPublished CVE record published
2026-06-16 22:32 UTCUpdated Record last modified

mod auth kerb mod auth kerb DOWNGRADE

Affected: 5.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.0

1. Check installed version

apt-cache policy mod-auth-kerb || rpm -q mod-auth-kerb || mod-auth-kerb --version

2. No fixed release: DOWNGRADE to a release before 5.0 (Debian / Ubuntu)

apt-cache madison mod-auth-kerb sudo apt install mod-auth-kerb=<VERSION_BEFORE_5.0> sudo apt-mark hold mod-auth-kerb

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

dnf --showduplicates list mod-auth-kerb sudo dnf downgrade mod-auth-kerb-<VERSION_BEFORE_5.0> sudo dnf versionlock add mod-auth-kerb

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-2006-5989?

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

Is CVE-2006-5989 being exploited?

CVE-2006-5989 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-2006-5989 affect?

CVE-2006-5989 affects mod auth kerb. Severity is medium (CVSS 5.0). Off-by-one error in the der_get_oid function in mod_auth_kerb 5.0 allows remote attackers to cause a denial of service (crash) via a crafted Kerberos message that triggers a heap-based buffer overflow in the component array.

How urgent is CVE-2006-5989?

Priority 40/100. EPSS top 10%: very likely to be exploited

References

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