Bug 1535554 (CVE-2018-5709)

Summary:	CVE-2018-5709 krb5: integer overflow in dbentry->n_key_data in kadmin/dbutil/dump.c
Product:	[Other] Security Response	Reporter:	Laura Pardo <lpardo>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	abokovoy, apintea, bkundal, bmaxwell, cdewolf, chazlett, csutherl, darran.lofthouse, dimitris, dosoudil, dpal, fgavrilo, gzaronik, jawilson, jclere, jondruse, jplans, jshepherd, j, lgao, mbabacek, mturk, myarboro, nalin, npmccallum, pgier, pjurak, pkis, ppalaga, psakar, pslavice, rharwood, rnetuka, rstancel, rsvoboda, sbose, scorneli, ssorce, sstavrev, twalsh, vtunka, weli, yozone
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-02-15 05:52:59 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1535555
Bug Blocks:	1535566

Description Laura Pardo 2018-01-17 15:38:46 UTC

An issue was discovered in MIT Kerberos 5 (aka krb5) through 1.16. There is a variable "dbentry->n_key_data" in kadmin/dbutil/dump.c that can store 16-bit data but unknowingly the developer has assigned a "u4" variable to it, which is for 32-bit data. An attacker can use this vulnerability to affect other artifacts of the database as we know that a Kerberos database dump file contains trusted data.

References:
https://github.com/poojamnit/Kerberos-V5-1.16-Vulnerabilities

Comment 1 Laura Pardo 2018-01-17 15:40:08 UTC

Created krb5 tracking bugs for this issue:

Affects: fedora-all [bug 1535555]

Comment 4 Huzaifa S. Sidhpurwala 2018-02-02 04:46:06 UTC

Statement:

This is essentially an integer truncation issue, and not an integer overflow. We have determined that this should not affect any other data allocated close to the  16-bit integer in question "dbentry-> n_key_data". Red Hat Product Security does not consider this issue as a security flaw.