CVE-2017-11368

Publication date 9 August 2017

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

In MIT Kerberos 5 (aka krb5) 1.7 and later, an authenticated attacker can cause a KDC assertion failure by sending invalid S4U2Self or S4U2Proxy requests.

From the Ubuntu Security Team

It was discovered that Kerberos incorrectly handled certain S4U2Self or S4U2Proxy requests. A remote authenticated attacker could possibly use this issue to cause a denial of service.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
krb5	21.04 hirsute	Not affected
	20.10 groovy	Not affected
	20.04 LTS focal	Not affected
	19.10 eoan	Not affected
	19.04 disco	Not affected
	18.10 cosmic	Not affected
	18.04 LTS bionic	Not affected
	17.10 artful	Not affected
	17.04 zesty	Ignored end of life
	16.04 LTS xenial	Fixed 1.13.2+dfsg-5ubuntu2.1
	14.04 LTS trusty	Fixed 1.12+dfsg-2ubuntu5.4

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
krb5	Upstream: https://github.com/krb5/krb5/pull/678/commits/a860385dd8fbd239fdb31b347e07f4e6b2fbdcc2

Severity score breakdown

Parameter	Value
Base score	6.5 · Medium
Attack vector	Network
Attack complexity	Low
Privileges required	Low
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	None
Availability impact	High
Vector	CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H