Headline
CVE-2023-42822: Unchecked access to font glyph info
xrdp is an open source remote desktop protocol server. Access to the font glyphs in xrdp_painter.c is not bounds-checked . Since some of this data is controllable by the user, this can result in an out-of-bounds read within the xrdp executable. The vulnerability allows an out-of-bounds read within a potentially privileged process. On non-Debian platforms, xrdp tends to run as root. Potentially an out-of-bounds write can follow the out-of-bounds read. There is no denial-of-service impact, providing xrdp is running in forking mode. This issue has been addressed in release 0.9.23.1. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Summary
Out-of-bounds read and potential out-od-bounds write in access to font glyphs.
Details
Access to the font glyphs in xrdp_painter.c is not bounds-checked . Since some of this data is controllable by the user, this can result in an out-of-bounds read within the xrdp executable.
Impact
The vulnerability allows an out-of-bounds read within a potentially privileged process. On non-Debian platforms, xrdp runs as root.
Potentially an out-of-bounds write can follow the out-of-bounds read.
There is no denial-of-service impact, providing xrdp is running in forking mode.
Related news
Ubuntu Security Notice 6474-1 - It was discovered that xrdp incorrectly handled validation of client-supplied data, which could lead to out-of-bounds reads. An attacker could possibly use this issue to crash the program or extract sensitive information. It was discovered that xrdp improperly handled session establishment errors. An attacker could potentially use this issue to bypass the OS-level session restrictions by PAM.