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KerberosApplication · Mit

CVE-2009-4212

HIGH · 10.0 CVSS v2.0 Published 2010-01-13
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

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
Multiple integer underflows in the (1) AES and (2) RC4 decryption functionality in the crypto library in MIT Kerberos 5 (aka krb5) 1.3 through 1.6.3, and 1.7 before 1.7.1, allow remote attackers to cause a denial of service (daemon crash) or possibly execute arbitrary code by providing ciphertext with a length that is too short to be valid.

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
How this class of weakness works · CWE-189

A legacy NVD category grouping numeric mistakes — overflows, truncation, sign errors — where a miscalculated value goes on to drive a dangerous decision such as a memory allocation or a bounds check. It is a bucket rather than one specific bug. Remediation is checked arithmetic and validating any computed size or index before it is used.

General guidance for the numeric errors class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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:= 1.3= 1.3.1= 1.3.2= 1.3.3= 1.3.4= 1.3.5= 1.3.6= 1.4= 1.4.1= 1.4.2= 1.4.3= 1.4.4

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
Complete
Integrity
Complete
Availability
Complete

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

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.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch web.mit.edu →
Recommended fix High confidence

MIT Kerberos 5 version 1.7.1 or later

  1. Identify the currently installed MIT Kerberos 5 version using 'krb5-config --version' or checking package manager
  2. Upgrade to MIT Kerberos 5 version 1.7.1 or later which contains the fix for the integer underflow vulnerability
  3. For package managers: on RHEL/CentOS use 'yum update krb5-libs' or 'yum update krb5-server', on Debian/Ubuntu use 'apt-get update && apt-get install krb5-kdc krb5-admin-server'
  4. Verify the upgrade was successful by checking the installed version matches 1.7.1 or later
  5. Test Kerberos authentication functionality to ensure the upgrade did not break existing services
  6. Restart Kerberos services (krb5kdc, kadmind) if necessary to load the fixed libraries
Caveat Upgrade within the same major version (1.x) should be low-risk; verify compatibility with any custom GSS-API or krb5 application plugins

Generated from the published advisory — verify against the referenced sources before acting.

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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-2009-4212 in production — separate from our analysis above.

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What this is

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