dbcve.org
KerberosApplication · Mit

CVE-2018-5710

MEDIUM · 6.5 CVSS v3.0 Published 2018-01-16
Fix available
A fix is available. Upgrade to after 5-1.16 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable 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
An issue was discovered in MIT Kerberos 5 (aka krb5) through 1.16. The pre-defined function "strlen" is getting a "NULL" string as a parameter value in plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c in the Key Distribution Center (KDC), which allows remote authenticated users to cause a denial of service (NULL pointer dereference) via a modified kadmin client.

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

In MIT Kerberos 5 (krb5) through 1.16, the ldap_principal2.c file in the LDAP KDB plugin passes a NULL string to the standard strlen() function without validation. When a remote authenticated attacker modifies a kadmin client to send a NULL string parameter, the KDC crashes due to NULL pointer dereference in strlen, causing denial of service.

MitigationApply the vendor patch for CVE-2018-5710 which adds proper NULL checking before calling strlen() in ldap_principal2.c. Until patched, monitor for KDC crashes and restrict kadmin access to trusted users only.

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:<= 5-1.16

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
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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 version
    Run 'krb5-config --version' or check the package manager for the krb5-server package version
    Affected if The version is 1.16 or lower (any version through 1.16 is affected)
  2. Determine if LDAP KDB plugin is in use
    Inspect the KDC configuration (typically kdc.conf or kdc.conf.in) for ldap_db_module or ldap_kerberos_container_dn settings, or check for LDAP-related entries in the realm configuration
    Affected if The LDAP KDB plugin is configured and active - the vulnerability only triggers when using LDAP as the Kerberos database backend
  3. Verify kadmin service is accessible
    Check if the kadmin service is listening (typically on port 749) or if kadmind process is running. Review access controls in kadm5.acl if present
    Affected if kadmin is exposed to network or untrusted users - the attacker needs to send a crafted request via kadmin
  4. Review KDC crash logs
    Examine system logs (such as /var/log/messages, journalctl, or kerberos-specific logs) for recent KDC daemon crashes or segfaults, particularly around kadmin operations
    Affected if The KDC has crashed with a NULL pointer dereference in strlen - this indicates the vulnerability may have been exploited
  5. Check for NULL string handling in LDAP principal operations
    Inspect the ldap_principal2.c file in the MIT Kerberos source if available, looking for strlen() calls without prior NULL validation on string parameters from LDAP
    Affected if The source code shows strlen() called on potentially NULL strings without validation (fixed in patches after 1.16)

You are affected if you run MIT Kerberos version 1.16 or lower with the LDAP KDB plugin enabled and kadmin is accessible to authenticated attackers who could send NULL string parameters.

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
Upgrade available Upgrade to a release after 5-1.16
Interim mitigation

Apply the vendor patch for CVE-2018-5710 which adds proper NULL checking before calling strlen() in ldap_principal2.c. Until patched, monitor for KDC crashes and restrict kadmin access to trusted users only.

Fix this in Kerberos Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,808.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2018-5710 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2018-5710 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data