Bug 1964018 (CVE-2021-28906)

Summary:	CVE-2021-28906 libyang: NULL pointer dereference in read_yin_leaf()
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	mruprich, tkorbar
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	libyang 1.0.226	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in libyang. Missing checks in several read_yin_* functions lead to NULL pointer dereferences possibly allowing a remote attacker to crash an application that uses libyang with user-controlled YIN formats. The highest threat from this vulnerability is the service availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-10-28 12:28:46 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:	1964019, 1965260, 1965261
Bug Blocks:	1964021

Description Guilherme de Almeida Suckevicz 2021-05-24 14:46:39 UTC

In function read_yin_leaf() in libyang <= v1.0.225, it doesn't check whether the value of retval->ext[r] is NULL. In some cases, it can be NULL, which leads to the operation of retval->ext[r]->flags that results in a crash.

Reference:
https://github.com/CESNET/libyang/issues/1455

Comment 1 Guilherme de Almeida Suckevicz 2021-05-24 14:46:53 UTC

Created libyang tracking bugs for this issue:

Affects: fedora-all [bug 1964019]

Comment 2 Riccardo Schirone 2021-05-27 09:46:22 UTC

Upstream patch:
https://github.com/CESNET/libyang/commit/a3917d95d516e3de267d3cfa5d4d3715a90e8777

This is the same patch as CVE-2021-28902.