Bug 1767955 (CVE-2019-16866)

Summary:	CVE-2019-16866 unbound: uninitialized memory accesses leads to crash via a crafted NOTIFY query
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	pemensik, pj.pandit
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	unbound 1.9.4	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-10-25 22:12:06 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1779501
Bug Blocks:	1767957

Description Guilherme de Almeida Suckevicz 2019-11-01 17:55:14 UTC

Unbound before 1.9.4 accesses uninitialized memory, which allows remote attackers to trigger a crash via a crafted NOTIFY query. The source IP address of the query must match an access-control rule.

References:
https://nlnetlabs.nl/downloads/unbound/CVE-2019-16866.txt
https://github.com/NLnetLabs/unbound/blob/7dfbcdf276e7a1070978209d2533b3b8cc504f86/doc/Changelog

Comment 2 Huzaifa S. Sidhpurwala 2019-12-04 05:27:14 UTC

Statement:

This issue has been classified as having low security impact because:
- per default, unbound is not configured to listen on a public interface
- per default, the ACL is limited to localhost, so even if listening to a public interface, the crash cannot happen per default

It mostly affects people running unbound as a "public" DNS resolver. Using such configurations, unbound has no valuable secrets that could be obtained by a successful attack, so at best the server crashes and restarts, resulting in an empty DNS cache. Sustained sending of packets would result in a DoS though.

Comment 3 Huzaifa S. Sidhpurwala 2019-12-04 05:27:17 UTC

External References:

https://nlnetlabs.nl/downloads/unbound/CVE-2019-16866.txt