Bug 1849877 (CVE-2019-20839)

Summary: CVE-2019-20839 libvncserver: buffer overflow in ConnectClientToUnixSock()
Product: [Other] Security Response Reporter: Marian Rehak <mrehak>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: jadahl, negativo17, rdieter
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Last Closed: 2021-05-18 14:34:21 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1849878, 1849879, 1851032, 1851033    
Bug Blocks: 1849880    

Description Marian Rehak 2020-06-23 06:25:19 UTC
libvncclient/sockets.c in LibVNCServer before 0.9.13 has a buffer overflow via a long socket filename.

Upstream Reference:

https://github.com/LibVNC/libvncserver/commit/3fd03977c9b35800d73a865f167338cb4d05b0c1

Comment 1 Marian Rehak 2020-06-23 06:25:41 UTC
Created libvncserver tracking bugs for this issue:

Affects: epel-7 [bug 1849879]
Affects: fedora-all [bug 1849878]

Comment 2 Stefan Cornelius 2020-06-25 13:16:07 UTC
Statement:

This is only an issue if the "ConnectClientToUnixSock()" function is used directly with an overly long socket name. It's more common that the "ConnectToRFBServer()" function is used, which would prevent exploiting this flaw as it performs additional checks. Additionally, the buffer overflow is caught by compiled-in buffer overflow checks, limiting the impact to a crash.

Comment 6 Product Security DevOps Team 2021-05-18 14:34:21 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-2019-20839

Comment 7 errata-xmlrpc 2021-05-18 15:16:07 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:1811 https://access.redhat.com/errata/RHSA-2021:1811