Bug 2236306 (CVE-2023-40184)

Summary:	CVE-2023-40184 xdp: restriction bypass via improper session handling
Product:	[Other] Security Response	Reporter:	Chess Hazlett <chazlett>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	Keywords:	Security
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	xrdp 0.9.23	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2236307, 2236308
Bug Blocks:

Description Chess Hazlett 2023-08-30 21:18:49 UTC

 xrdp is an open source remote desktop protocol (RDP) server. In versions prior to 0.9.23 improper handling of session establishment errors allows bypassing OS-level session restrictions. The `auth_start_session` function can return non-zero (1) value on, e.g., PAM error which may result in in session restrictions such as max concurrent sessions per user by PAM (ex ./etc/security/limits.conf) to be bypassed. Users (administrators) don't use restrictions by PAM are not affected. This issue has been addressed in release version 0.9.23. Users are advised to upgrade. There are no known workarounds for this issue.

https://github.com/neutrinolabs/xrdp/security/advisories/GHSA-f489-557v-47jq
https://github.com/neutrinolabs/xrdp/commit/a111a0fdfe2421ef600e40708b5f0168594cfb23
https://github.com/neutrinolabs/xrdp/blame/9bbb2ec68f390504c32f2062847aa3d821a0089a/sesman/sesexec/session.c#L571C5-L571C19

Comment 1 Chess Hazlett 2023-08-30 21:19:05 UTC

Created xrdp tracking bugs for this issue:

Affects: epel-all [bug 2236308]
Affects: fedora-all [bug 2236307]