CVE-2018-20023

NameCVE-2018-20023
DescriptionLibVNC before 8b06f835e259652b0ff026898014fc7297ade858 contains CWE-665: Improper Initialization vulnerability in VNC Repeater client code that allows attacker to read stack memory and can be abuse for information disclosure. Combined with another vulnerability, it can be used to leak stack memory layout and in bypassing ASLR
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
ReferencesDLA-1617-1, DLA-1979-1, DSA-4383-1
NVD severitymedium
Debian Bugs916941

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
italc (PTS)stretch1:3.0.3+dfsg1-1+deb9u1fixed
libvncserver (PTS)stretch0.9.11+dfsg-1.3~deb9u4fixed
stretch (security)0.9.11+dfsg-1.3~deb9u6fixed
buster0.9.11+dfsg-1.3+deb10u4fixed
bullseye0.9.13+dfsg-2fixed
bookworm, sid0.9.13+dfsg-3fixed
veyon (PTS)buster4.1.7+repack1-1fixed
bookworm, sid, bullseye4.5.3+repack1-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
italcsourcejessie1:2.0.2+dfsg1-2+deb8u1DLA-1979-1
italcsourcestretch1:3.0.3+dfsg1-1+deb9u1
italcsource(unstable)(unfixed)
libvncserversourcejessie0.9.9+dfsg2-6.1+deb8u4DLA-1617-1
libvncserversourcestretch0.9.11+dfsg-1.3~deb9u1DSA-4383-1
libvncserversource(unstable)0.9.11+dfsg-1.2916941
veyonsource(unstable)4.1.4+repack1-1

Notes

https://github.com/LibVNC/libvncserver/issues/253
https://github.com/LibVNC/libvncserver/commit/8b06f835e259652b0ff026898014fc7297ade858
https://ics-cert.kaspersky.com/advisories/klcert-advisories/2018/12/19/klcert-18-033-libvnc-memory-leak/

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