fusermount in fuse 2.8.5 and earlier does not perform a chdir to / before performing a mount or umount, which allows local users to unmount arbitrary directories via unspecified vectors.

The remote Redhat Enterprise Linux 5 host has one or more packages installed that are affected by multiple vulnerabilities that have been acknowledged by the vendor but will not be patched.

  - fuse: unprivileged user can unmount arbitrary locations via symlink attack (CVE-2010-3879)

  - fuse: incorrect filtering of environment variables leading to privilege escalation (CVE-2015-3202)

  - fusermount in FUSE before 2.7.5, and 2.8.x before 2.8.2, allows local users to unmount an arbitrary FUSE     filesystem share via a symlink attack on a mountpoint. (CVE-2010-0789)

Note that Nessus has not tested for these issues but has instead relied on the package manager's report that the package is installed.

From Red Hat Security Advisory 2011:1083 :

Updated fuse packages that fix multiple security issues are now available for Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

FUSE (Filesystem in Userspace) can implement a fully functional file system in a user-space program. These packages provide the mount utility, fusermount, the tool used to mount FUSE file systems.

Multiple flaws were found in the way fusermount handled the mounting and unmounting of directories when symbolic links were present. A local user in the fuse group could use these flaws to unmount file systems, which they would otherwise not be able to unmount and that were not mounted using FUSE, via a symbolic link attack.
(CVE-2010-3879, CVE-2011-0541, CVE-2011-0542, CVE-2011-0543)

Note: The util-linux-ng RHBA-2011:0699 update must also be installed to fully correct the above flaws.

All users should upgrade to these updated packages, which contain backported patches to correct these issues.

Updated fuse packages that fix multiple security issues are now available for Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

FUSE (Filesystem in Userspace) can implement a fully functional file system in a user-space program. These packages provide the mount utility, fusermount, the tool used to mount FUSE file systems.

Multiple flaws were found in the way fusermount handled the mounting and unmounting of directories when symbolic links were present. A local user in the fuse group could use these flaws to unmount file systems, which they would otherwise not be able to unmount and that were not mounted using FUSE, via a symbolic link attack.
(CVE-2010-3879, CVE-2011-0541, CVE-2011-0542, CVE-2011-0543)

Note: The util-linux-ng RHBA-2011:0699 update must also be installed to fully correct the above flaws.

All users should upgrade to these updated packages, which contain backported patches to correct these issues.

It was discovered that FUSE would incorrectly follow symlinks when checking mountpoints under certain conditions. A local attacker, with access to use FUSE, could unmount arbitrary locations, leading to a denial of service.

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Severity
199383	RHEL 5 : fuse (Unpatched Vulnerability)	Nessus	Red Hat Local Security Checks	critical
68309	Oracle Linux 6 : fuse (ELSA-2011-1083)	Nessus	Oracle Linux Local Security Checks	medium
55635	RHEL 6 : fuse (RHSA-2011:1083)	Nessus	Red Hat Local Security Checks	medium
52479	Ubuntu 8.04 LTS / 9.10 / 10.04 LTS / 10.10 : fuse vulnerabilities (USN-1077-1)	Nessus	Ubuntu Local Security Checks	low

Detections

Analytics

CVE-2011-0542

high

Tenable Plugins

critical

medium

medium

low