Bug 1872737 (CVE-2020-24240)

Summary:	CVE-2020-24240 bison: use-after-free via crafted input file containing a NULL byte can lead to DoS
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:	arjun.is, ashankar, emachado, me, pfrankli
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	bison 3.7.1	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-08-28 01:17:29 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:	1872738
Bug Blocks:	1872739

Description Guilherme de Almeida Suckevicz 2020-08-26 14:13:44 UTC

GNU Bison 3.7 has a use after free (UAF) vulnerability. A local attacker may execute bison with crafted input file containing a NULL byte, which could triggers UAF and thus cause system crash.

Reference:
https://lists.gnu.org/r/bug-bison/2020-07/msg00051.html

Upstream patch:
https://github.com/akimd/bison/commit/be95a4fe2951374676efc9454ffee8638faaf68d

Comment 1 Guilherme de Almeida Suckevicz 2020-08-26 14:14:05 UTC

Created bison tracking bugs for this issue:

Affects: fedora-all [bug 1872738]

Comment 3 Todd Cullum 2020-08-27 20:03:59 UTC

Statement:

bison as shipped in Red Hat Enterprise Linux 7 and 8 does not reproduce this flaw. It properly detects the NULL byte and errors out accordingly instead of causing use-after-free. This is likely due to introduction of vulnerable code in a more recent version of bison.

Comment 4 Product Security DevOps Team 2020-08-28 01:17:29 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2020-24240