fuse 2.8.5 and earlier does not properly handle when /etc/mtab cannot be updated, which allows local users to unmount arbitrary directories via a symlink attack.

References

• https://nvd.nist.gov/vuln/detail/CVE-2011-0541
• http://fuse.git.sourceforge.net/git/gitweb.cgi?p=fuse/fuse;a=commit;h=bf5ffb5fd8558bd799791834def431c0cee5a11f
• http://lists.opensuse.org/opensuse-security-announce/2011-04/msg00000.html
• http://www.openwall.com/lists/oss-security/2011/02/02/2
• http://www.openwall.com/lists/oss-security/2011/02/03/5
• http://www.openwall.com/lists/oss-security/2011/02/08/4
• http://fuse.git.sourceforge.net/git/gitweb.cgi?p=fuse/fuse%3Ba=commit%3Bh=bf5ffb5fd8558bd799791834def431c0cee5a11f