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FedoraOperating system · Fedoraproject

CVE-2007-4000

HIGH · 8.5 CVSS v2.0 Published 2007-09-05
Fix available
A fix is available. Upgrade to after 1.6.2 or later.
See remediation →
91/100
Remediation priority · Urgent
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
The kadm5_modify_policy_internal function in lib/kadm5/srv/svr_policy.c in the Kerberos administration daemon (kadmind) in MIT Kerberos 5 (krb5) 1.5 through 1.6.2 does not properly check return values when the policy does not exist, which might allow remote authenticated users with the "modify policy" privilege to execute arbitrary code via unspecified vectors that trigger a write to an uninitialized pointer.

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 versions 1.5 through 1.6.2, the kadm5_modify_policy_internal function in the kadmind daemon fails to properly validate return values when a policy does not exist. This results in a write to an uninitialized pointer, which an authenticated attacker with 'modify policy' privilege could exploit to achieve arbitrary code execution with the privileges of the kadmind process.

MitigationUpgrade to krb5 version 1.6.3 or later which contains the fix. Until patched, restrict or disable the 'modify policy' privilege for untrusted principals and limit network access to kadmind ports (749/750).

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
FedoraOperating system
Affected:= 7
Kerberos 5Application
Affected:>= 1.5, <= 1.6.2

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
M
Authentication
Single
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:M/Au:S/C:C/I:C/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. Check installed MIT Kerberos 5 version
    Run 'krb5-config --version' or check the krb5-libs/krb5-server package version with your system package manager (e.g., 'rpm -q krb5-libs' or 'dpkg -l krb5').
    Affected if The installed version is 1.5, 1.6, 1.6.1, or 1.6.2 (any version from 1.5 through 1.6.2 inclusive).
  2. Determine if kadmind daemon is running
    Check for the kadmind process: run 'ps aux | grep kadmind' or check if ports 749/tcp or 750/tcp are open with 'netstat -anp | grep -E "749|750"' or 'ss -tlnp | grep -E "749|750"'.
    Affected if The kadmind daemon is actively running and listening on network ports.
  3. Identify principals with modify policy privilege
    Use kadmin to list principals with the 'modify' privilege on policies: run 'kadmin -l' then 'listprincs *' to see principals, then check ACL files (typically /var/kerberos/krb5kdc/kadm5.acl) for entries granting 'modify' policy rights.
    Affected if Any principal (other than the kadmin/admin principal) has 'modify' or 'all' policy privileges defined in the kadmind ACL.
  4. Check if policy validation can be triggered
    This vulnerability triggers when modifying a policy that does not exist. Use kadmin to attempt listing policies with 'getpol <nonexistent_policy_name>' or try 'modpol <nonexistent_policy> -maxlife <value>' to observe behavior.
    Affected if Kadmind is accessible and accepts modify policy operations (authenticated users with modify privilege can trigger the uninitialized pointer write).

You are affected if you run MIT Kerberos 5 versions 1.5 through 1.6.2 with kadmind daemon active and any principal has modify policy privileges accessible over the network.

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 1.6.2
Interim mitigation

Upgrade to krb5 version 1.6.3 or later which contains the fix. Until patched, restrict or disable the 'modify policy' privilege for untrusted principals and limit network access to kadmind ports (749/750).

Fix this in Fedora Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,840
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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-2007-4000 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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