Shiftfs, an out-of-tree stacking file system included in Ubuntu Linux kernels, did not properly handle faults occurring during copy_from_user() correctly. These could lead to either a double-free situation or memory not being freed at all. An attacker could use this to cause a denial of service (kernel memory exhaustion) or gain privileges via executing arbitrary code. AKA ZDI-CAN-13562.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Shiftfs, an out-of-tree stacking file system included in Ubuntu Linux kernels, did not properly handle     faults occurring during copy_from_user() correctly. These could lead to either a double-free situation or     memory not being freed at all. An attacker could use this to cause a denial of service (kernel memory     exhaustion) or gain privileges via executing arbitrary code. AKA ZDI-CAN-13562. (CVE-2021-3492)

Note that Nessus relies on the presence of the package as reported by the vendor.

The remote Ubuntu 18.04 LTS / 20.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-4917-1 advisory.

    It was discovered that the overlayfs implementation in the Linux kernel did not properly validate the     application of file system capabilities with respect to user namespaces. A local attacker could use this     to gain elevated privileges. (CVE-2021-3493)

    Vincent Dehors discovered that the shiftfs file system in the Ubuntu Linux kernel did not properly handle     faults in copy_from_user() when passing through ioctls to an underlying file system. A local attacker     could use this to cause a denial of service (memory exhaustion) or execute arbitrary code. (CVE-2021-3492)

    Piotr Krysiuk discovered that the BPF JIT compiler for x86 in the Linux kernel did not properly validate     computation of branch displacements in some situations. A local attacker could use this to cause a denial     of service (system crash) or possibly execute arbitrary code. (CVE-2021-29154)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Ubuntu 20.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-4915-1 advisory.

    It was discovered that the overlayfs implementation in the Linux kernel did not properly validate the     application of file system capabilities with respect to user namespaces. A local attacker could use this     to gain elevated privileges. (CVE-2021-3493)

    Vincent Dehors discovered that the shiftfs file system in the Ubuntu Linux kernel did not properly handle     faults in copy_from_user() when passing through ioctls to an underlying file system. A local attacker     could use this to cause a denial of service (memory exhaustion) or execute arbitrary code. (CVE-2021-3492)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Type	Severity
244648	Linux Distros Unpatched Vulnerability : CVE-2021-3492	Nessus	Misc.	Local	high
148690	Ubuntu 18.04 LTS / 20.04 LTS : Linux kernel vulnerabilities (USN-4917-1)	Nessus	Ubuntu Local Security Checks	Local	high
148689	Ubuntu 20.04 LTS : Linux kernel (OEM) vulnerabilities (USN-4915-1)	Nessus	Ubuntu Local Security Checks	Local	high

Detections

Analytics

CVE-2021-3492

high

Tenable Plugins

high

high

high