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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2023-1386
• https://access.redhat.com/security/cve/CVE-2023-1386
• https://bugzilla.redhat.com/show_bug.cgi?id=2223985
• https://security.netapp.com/advisory/ntap-20230831-0005
• v9fs/linux#29
• GHSA-ppj8-867g-rgjr