Bug 2223985 (CVE-2023-1386)

Summary:	CVE-2023-1386 QEMU: 9pfs: SUID/SGID bits not dropped on file write
Product:	[Other] Security Response	Reporter:	Mauro Matteo Cascella <mcascell>
Component:	vulnerability	Assignee:	Nobody <nobody>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	ddepaula, jen, jferlan, jmaloy, knoel, mkenneth, mrezanin, mst, pbonzini, virt-maint, ymankad
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the 9p passthrough filesystem (9pfs) implementation in QEMU. When a local user in the guest writes an executable file with SUID or SGID, none of these privileged bits are correctly dropped. As a result, in rare circumstances, this flaw could be used by malicious users in the guest to elevate their privileges within the guest and help a host local user to elevate privileges on the host.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2023-07-19 13:03:49 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2223986
Bug Blocks:	2175653

Description Mauro Matteo Cascella 2023-07-19 13:03:13 UTC

A flaw was discovered in 9pfs. Jietao Xiao and his team found that when a local user in the guest tries to write an executable file with SUID or SGID, none of these privileged bits are correctly dropped. As a result, in rare circumstances(exist an executable file owned by root, writable by others, has SUID/SGID bits), this flaw could be used by malicious users in the guest to elevate their privileges within the guest and help a host's local user to elevate privileges on the host.

Upstream issue:
https://github.com/v9fs/linux/issues/29

Comment 1 Mauro Matteo Cascella 2023-07-19 13:03:32 UTC

Created qemu tracking bugs for this issue:

Affects: fedora-all [bug 2223986]