oss-sec mailing list archives
Re: [CVE-2021-3493] Ubuntu Linux kernel overlayfs fs caps privilege escalation
From: Salvatore Bonaccorso <carnil () debian org>
Date: Fri, 16 Apr 2021 16:53:50 +0200
Hi Steve, On Thu, Apr 15, 2021 at 02:31:14PM -0700, Steve Beattie wrote:
Hello, An independent security researcher reported via the SSD Secure Disclosure program that the overlayfs stacking file system within the Linux kernel as used within Ubuntu did not properly validate the application of file capabilities against user namespaces. This issue is likely Ubuntu specific, as Ubuntu carries a patch to enable unprivileged overlayfs mounts. The combination of that patch plus allowing unprivileged user namespaces by default in Ubuntu allows an unprivileged attacker to gain elevated privileges. A commit that addresses the issue was applied in the upstream kernel: 7c03e2cda4a5 ("vfs: move cap_convert_nscap() call into vfs_setxattr()") (v5.10)
For completeness, this though was in v5.11-rc1 right? Regards, Salvatore
Current thread:
- [CVE-2021-3493] Ubuntu Linux kernel overlayfs fs caps privilege escalation Steve Beattie (Apr 16)
- Re: [CVE-2021-3493] Ubuntu Linux kernel overlayfs fs caps privilege escalation Salvatore Bonaccorso (Apr 16)
- Re: [CVE-2021-3493] Ubuntu Linux kernel overlayfs fs caps privilege escalation Steve Beattie (Apr 16)
- Re: [CVE-2021-3493] Ubuntu Linux kernel overlayfs fs caps privilege escalation Salvatore Bonaccorso (Apr 16)