Bug 1985246 (CVE-2020-36430)

Summary:	CVE-2020-36430 libass: heap-based buffer overflow in decode_chars because the wrong integer data type is used for subtraction
Product:	[Other] Security Response	Reporter:	Marian Rehak <mrehak>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	martin.sourada, rhel8-maint
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:	2021-10-28 05:28:38 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:	1985247, 1985248
Bug Blocks:

Description Marian Rehak 2021-07-23 08:52:06 UTC

libass 0.15.x before 0.15.1 has a heap-based buffer overflow in decode_chars (called from decode_font and process_text) because the wrong integer data type is used for subtraction.

References:

https://github.com/libass/libass/commit/017137471d0043e0321e377ed8da48e45a3ec632
https://github.com/google/oss-fuzz-vulns/blob/main/vulns/libass/OSV-2020-2099.yaml
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=26674

Comment 1 Marian Rehak 2021-07-23 08:52:41 UTC

Created libass tracking bugs for this issue:

Affects: epel-all [bug 1985248]
Affects: fedora-all [bug 1985247]