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KerberosApplication · Mit

CVE-2011-0281

MEDIUM · 5.0 CVSS v2.0 Published 2011-02-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
59/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The unparse implementation in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) 1.6.x through 1.9, when an LDAP backend is used, allows remote attackers to cause a denial of service (file descriptor exhaustion and daemon hang) via a principal name that triggers use of a backslash escape sequence, as demonstrated by a \n sequence.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A denial of service vulnerability exists in the KDC unparse function in MIT Kerberos 5 versions 1.6 through 1.9 when using an LDAP backend. Attackers can trigger file descriptor exhaustion by sending principal names containing backslash escape sequences (such as \n), causing the daemon to hang.

MitigationUpgrade to krb5 1.10 or later, or apply vendor patches. If immediate patching is not possible, consider restricting access to the KDC and implementing network-level filtering to limit unusual principal name patterns.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
KerberosApplication
Affected:= 5-1.6.3
Kerberos 5Application
Affected:= 1.6= 1.6.1= 1.6.2= 1.7= 1.7.1= 1.8= 1.8.1= 1.8.2= 1.8.3= 1.9

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Authentication
None
Confidentiality
None
Integrity
None
Availability
Partial

AV:N/AC:L/Au:N/C:N/I:N/A:P

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed MIT Kerberos 5 version
    Run 'krb5-config --version' or check the package manager (rpm -q krb5-server or dpkg -l krb5-kdc)
    Affected if Version is 1.6, 1.6.1, 1.6.2, 1.6.3, 1.7, 1.7.1, 1.8, 1.8.1, 1.8.2, 1.8.3, or 1.9
  2. Verify KDC service is running
    Check for krb5kdc process (ps aux | grep krb5kdc) or query systemd (systemctl status krb5-kdc)
    Affected if KDC daemon is active and serving requests
  3. Confirm LDAP backend is in use
    Examine /var/kerberos/krb5kdc/kdc.conf or /etc/krb5.conf for 'ldap_kdc_dn' or 'ldap_kerberos_container_dn' directives under the [kdcdefaults] or [realms] sections
    Affected if LDAP is configured as the Kerberos database backend (not db2 or other file-based backends)

You are affected if you run MIT Kerberos 5 versions 1.6 through 1.9 with an LDAP backend configured and the KDC is actively running.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to krb5 1.10 or later, or apply vendor patches. If immediate patching is not possible, consider restricting access to the KDC and implementing network-level filtering to limit unusual principal name patterns.

Fix this in Kerberos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2011-0281 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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