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Kerberos 5Application · Mit

CVE-2011-1527

HIGH · 7.8 CVSS v2.0 Published 2011-10-20
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
87/100
Remediation priority · High
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 kdb_ldap plugin in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) 1.9 through 1.9.1, when the LDAP back end is used, allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via a kinit operation with incorrect string case for the realm, related to the is_principal_in_realm, krb5_set_error_message, krb5_ldap_get_principal, and process_as_req functions.

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

The kdb_ldap plugin in MIT Kerberos 5 KDC versions 1.9 through 1.9.1 contains a NULL pointer dereference vulnerability when the LDAP backend processes a kinit operation with incorrect string case for the realm name. This causes the KDC daemon to crash, resulting in denial of service.

MitigationUpdate MIT Kerberos 5 to version 1.9.2 or later which contains the fix. If immediate patching is not possible, ensure that realm names are passed with correct casing to prevent the NULL pointer dereference.

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
Kerberos 5Application
Affected:= 1.9= 1.9.1

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
Complete

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

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 MIT Kerberos 5 KDC version
    Run 'kinit --version' or 'kdc --version' to determine the installed MIT Kerberos 5 version
    Affected if Version is 1.9 or 1.9.1
  2. Check if kdb_ldap plugin is configured
    Inspect the KDC configuration file (typically /etc/krb5.conf or /etc/kdc.conf) for 'db_module' or 'ldap' entries in the [kdcdefaults] or [realms] sections
    Affected if The kdb_ldap module is specified as the database backend
  3. Verify LDAP backend is active
    Check for LDAP-related configuration in the KDC database module settings, typically in /etc/krb5.conf or a separate kdc.conf file under the [dbmodules] section
    Affected if LDAP is configured as the KDC database backend
  4. Confirm KDC daemon is using the LDAP plugin
    Review the KDC startup configuration or logs to confirm the kdb_ldap plugin is loaded at runtime
    Affected if The kdb_ldap plugin is loaded and actively used by the KDC

You are affected if you are running MIT Kerberos 5 versions 1.9 or 1.9.1 with the kdb_ldap (LDAP backend) plugin enabled and the KDC is actively using it

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

Update MIT Kerberos 5 to version 1.9.2 or later which contains the fix. If immediate patching is not possible, ensure that realm names are passed with correct casing to prevent the NULL pointer dereference.

Fix this in Kerberos 5 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
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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-2011-1527 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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