Bug 1849877 (CVE-2019-20839) - CVE-2019-20839 libvncserver: "ConnectClientToUnixSock()" buffer overflow
Summary: CVE-2019-20839 libvncserver: "ConnectClientToUnixSock()" buffer overflow
Keywords:
Status: NEW
Alias: CVE-2019-20839
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1849879 1851032 1849878 1851033
Blocks: 1849880
TreeView+ depends on / blocked
 
Reported: 2020-06-23 06:25 UTC by Marian Rehak
Modified: 2020-06-25 14:10 UTC (History)
3 users (show)

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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.


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