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Kerberos 5Application · Mit

CVE-2008-0948

HIGH · 9.3 CVSS v2.0 Published 2008-03-19
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
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
Buffer overflow in the RPC library (lib/rpc/rpc_dtablesize.c) used by libgssrpc and kadmind in MIT Kerberos 5 (krb5) 1.2.2, and probably other versions before 1.3, when running on systems whose unistd.h does not define the FD_SETSIZE macro, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code by triggering a large number of open file descriptors.

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

Buffer overflow in MIT Kerberos 5's RPC library (lib/rpc/rpc_dtablesize.c) when FD_SETSIZE macro is not defined by the system's unistd.h. Attackers can trigger the vulnerability by opening a large number of file descriptors, potentially causing denial of service or remote code execution.

MitigationDefine FD_SETSIZE in the code before use, or add a compile-time check to ensure the macro is properly defined by the system; upgrade to krb5 1.3 or later which contains the fix.

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:= 1.2.2

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
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:M/Au:N/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. Identify MIT Kerberos 5 version
    Run 'krb5-config --version' or check the package version via your system package manager (e.g., 'rpm -q krb5' or 'dpkg -l krb5')
    Affected if The installed version is exactly 1.2.2 (earlier versions may also be affected, but 1.2.2 is the confirmed vulnerable version)
  2. Verify FD_SETSIZE macro definition
    Check if FD_SETSIZE is defined in your system's unistd.h header file. Run: 'grep -n FD_SETSIZE /usr/include/unistd.h' or inspect the header file directly
    Affected if FD_SETSIZE is NOT defined in unistd.h - the vulnerability requires this macro to be missing for the buffer overflow to occur
  3. Inspect the vulnerable RPC source file
    Locate and examine lib/rpc/rpc_dtablesize.c in the Kerberos source tree if available. Look for code that uses FD_SETSIZE without prior definition or uses it in array sizing for fd_set operations
    Affected if The file contains code that uses FD_SETSIZE without first checking or defining it, allowing unchecked buffer allocation based on file descriptor limits
  4. Test file descriptor limit behavior
    Attempt to open a large number of file descriptors (e.g., via a test script that loops opening files or sockets) and observe if the application behaves unexpectedly or crashes
    Affected if Opening many file descriptors causes abnormal behavior, crashes, or buffer overflow indicators in Kerberos RPC operations

A system is affected if MIT Kerberos 5 version 1.2.2 is installed AND FD_SETSIZE is not properly defined in the system headers, allowing the RPC library's fd_set table to overflow when many file descriptors are opened.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Define FD_SETSIZE in the code before use, or add a compile-time check to ensure the macro is properly defined by the system; upgrade to krb5 1.3 or later which contains the fix.

Recommended fix High confidence

MIT Kerberos 5 version 1.3 or later (recommended: latest stable 1.4.x or 1.5.x series)

  1. 1. Identify the current installed version of MIT Kerberos 5 (krb5) using: rpm -q krb5 or dpkg -l krb5
  2. 2. If version is 1.2.2 or any version before 1.3, plan for upgrade
  3. 3. Backup current Kerberos configuration files (/etc/krb5.conf, /var/kerberos/krb5kdc/kdc.conf, and any keytabs)
  4. 4. Upgrade the krb5 packages to version 1.3 or later using your OS package manager (e.g., yum update krb5, apt-get install krb5)
  5. 5. If OS packages are unavailable, download MIT Kerberos source from http://web.mit.edu/kerberos/ and compile version 1.3, 1.4, or latest stable
  6. 6. After upgrade, verify the new version: kinit --version
  7. 7. Test Kerberos authentication and kadmind functionality to ensure the RPC library works correctly
  8. 8. Restart any services using Kerberos (krb5kdc, kadmind, etc.)
Caveat Major version upgrades of Kerberos may require configuration file updates and keytab regeneration; test thoroughly in non-production environment first

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

Fix this in Kerberos 5 Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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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-2008-0948 in production — separate from our analysis above.

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