Bug 1902011 (CVE-2020-27818)

Summary: CVE-2020-27818 pngcheck: global buffer overflow was discovered in check_chunk_name function via crafted pngfile
Product: [Other] Security Response Reporter: Marian Rehak <mrehak>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: code
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in the check_chunk_name() function of pngcheck. This flaw allows an attacker who can pass a malicious file to be processed by pngcheck to cause a temporary denial of service. The highest threat from this vulnerability is to system availability.
Story Points: ---
Clone Of: Environment:
Last Closed: 2020-11-26 17:33:53 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 1902012    
Bug Blocks: 1902014    

Description Marian Rehak 2020-11-26 15:16:37 UTC
A global buffer overflow was discovered in check_chunk_name function in pngcheck-2.4.0 via a crafted png file.



Comment 1 Marian Rehak 2020-11-26 15:17:03 UTC
Created pngcheck tracking bugs for this issue:

Affects: fedora-all [bug 1902012]

Comment 2 Product Security DevOps Team 2020-11-26 17:33:53 UTC
This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.

Comment 4 Todd Cullum 2020-11-30 19:01:28 UTC
Flaw summary:

When pngcheck is provided a crafted input file, it could cause a global-buffer-overflow -> out-of-bounds read, due to improper use of casts in the check_chunk_name() function of pngcheck-2.4.0/pngcheck.c. Red Hat Product Security has designated this as a Low severity issue because an attacker would likely need to social engineer a user or already have access to a victim system, and exploiting this flaw would likely only lead to temporary denial of service (application crash).

Comment 5 Todd Cullum 2020-11-30 19:03:19 UTC

To mitigate this flaw, do not provide input files from untrusted sources to pngcheck.