| Description: | The Btrfs implementation in the Linux kernel before 3.19 does not ensure that the visible xattr state is consistent with a requested replacement, which allows local users to bypass intended ACL settings and gain privileges via standard filesystem operations (1) during an xattr-replacement time window, related to a race condition, or (2) after an xattr-replacement attempt that fails because the data does not fit. Alexandre Oliva reported a race condition flaw in the btrfs file system's handling of extended attributes (xattrs). A local attacker could exploit this flaw to bypass ACLs and potentially escalate privileges.
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