Bug 2268418 (CVE-2024-1931)

Summary:	CVE-2024-1931 unbound: Infinite loop due to improper EDE message size check
Product:	[Other] Security Response	Reporter:	Pedro Sampaio <psampaio>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	bmason
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	unbound 1.19.2	Doc Type:	If docs needed, set a value
Doc Text:	A vulnerability was found in Unbound. The issue arises due to a flaw in the handling of Extended DNS Error (EDE) records when the 'ede: yes' option is enabled, a non-default configuration. Specifically, an unchecked condition in the code can trigger an infinite loop when attempting to trim the text fields of EDE records to fit within the client's buffer size. This vulnerability could potentially lead to denial of service (DoS) as the infinite loop consumes system resources, impacting the availability of the Unbound DNS resolver.	Story Points:	---
Clone Of:		Environment:
Last Closed:		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:	2268419
Bug Blocks:	2268420

Description Pedro Sampaio 2024-03-07 12:20:04 UTC

NLnet Labs Unbound version 1.18.0 up to and including version 1.19.1 contain a vulnerability that can cause denial of service by a certain code path that can lead to an infinite loop. Unbound 1.18.0 introduced a feature that removes EDE records from responses with size higher than the client's advertised buffer size. Before removing all the EDE records however, it would try to see if trimming the extra text fields on those records would result in an acceptable size while still retaining the EDE codes. Due to an unchecked condition, the code that trims the text of the EDE records could loop indefinitely. This happens when Unbound would reply with attached EDE information on a positive reply and the client's buffer size is smaller than the needed space to include EDE records. The vulnerability can only be triggered when the 'ede: yes' option is used; non default configuration. From version 1.19.2 on, the code is fixed to avoid looping indefinitely.

References:

https://www.nlnetlabs.nl/downloads/unbound/CVE-2024-1931.txt

Comment 1 Pedro Sampaio 2024-03-07 12:20:19 UTC

Created unbound tracking bugs for this issue:

Affects: fedora-all [bug 2268419]