# CVE-1999-0143: MIT Kerberos 4 session key forgery and masquerade

Source: https://junglewise.ai/threats/cve-1999-0143-mit-kerberos-4-session-key-forgery-and-masquerade  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 1996-02-21. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-1999-0143 · Severity: medium · CVSS 4.6 · Published 1996-02-21

A security flaw in the Kerberos 4 authentication system allows an attacker to impersonate other users. Kerberos is a service used to verify identities across a network; by breaking and generating session keys, an unauthorized person could gain access to sensitive data or systems by pretending to be a legitimate user. This could lead to unauthorized data access and a breach of accountability within the organization.

Vendors: [Mit](https://junglewise.ai/threats/vendors/mit).

## Quick answers

**Is CVE-1999-0143 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-1999-0143 being exploited in the wild.

**How severe is CVE-1999-0143?** Medium severity, with a CVSS score of 4.6, published 21 February 1996.

**Which products and versions are affected?** MIT Kerberos 4; Sun Microsystems Solaris 2.3, 2.4; Sun Microsystems SunOS 5.3, 5.4.

**Is there a fix for CVE-1999-0143?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-1999-0143 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-1999-0143?** Check whether you run Mit Kerberos 4. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability exists in Kerberos 4 key servers related to the generation and handling of session keys. An attacker with local access can exploit weaknesses in the key generation process to derive or forge session keys. Successful exploitation allows the attacker to masquerade as any other user within the Kerberos realm, bypassing standard authentication controls. This issue affects MIT Kerberos 4 implementations and integrated versions found in legacy operating systems like SunOS and Solaris. Modern versions of Kerberos (v5) address these fundamental cryptographic weaknesses.

## Affected products

- MIT Kerberos 4
- Sun Microsystems Solaris 2.3, 2.4
- Sun Microsystems SunOS 5.3, 5.4

## Timeline

- 1996-02-21: disclosed: Initial publication date in NVD

## References

- [https://exchange.xforce.ibmcloud.com/vulnerabilities/CVE-1999-0143](https://exchange.xforce.ibmcloud.com/vulnerabilities/CVE-1999-0143)

## Related threats

- [MIT Kerberos 4 Information Disclosure via Malformed UDP Packet](https://junglewise.ai/threats/cve-1999-1099-mit-kerberos-4-information-disclosure-via-malformed-udp-packet)