UBUNTU-CVE-2020-16120

    Dashboard / Vulnerabilities / UBUNTU-CVE-2020-16120

    UBUNTU-CVE-2020-16120

    Published: 13 Oct 2020Last Modified: 9 Sept 2026
    Upstream:
    CVE-2020-16120

    Summary:

    Details: Overlayfs did not properly perform permission checking when copying up files in an overlayfs and could be exploited from within a user namespace, if, for example, unprivileged user namespaces were allowed. It was possible to have a file not readable by an unprivileged user to be copied to a mountpoint controlled by the user, like a removable device. This was introduced in kernel version 4.19 by commit d1d04ef ("ovl: stack file ops"). This was fixed in kernel version 5.8 by commits 56230d9 ("ovl: verify permissions in ovl_path_open()"), 48bd024 ("ovl: switch to mounter creds in readdir") and 05acefb ("ovl: check permission to open real file"). Additionally, commits 130fdbc ("ovl: pass correct flags for opening real directory") and 292f902 ("ovl: call secutiry hook in ovl_real_ioctl()") in kernel 5.8 might also be desired or necessary. These additional commits introduced a regression in overlay mounts within user namespaces which prevented access to files with ownership outside of the user namespace. This regression was mitigated by subsequent commit b6650da ("ovl: do not fail because of O_NOATIMEi") in kernel 5.11.

    References: https://ubuntu.com/security/CVE-2020-16120, https://www.openwall.com/lists/oss-security/2020/10/13/6, https://ubuntu.com/security/notices/USN-4578-1, https://ubuntu.com/security/notices/USN-4577-1, https://ubuntu.com/security/notices/USN-4576-1, https://www.cve.org/CVERecord?id=CVE-2020-16120

    Affected packages

    Package

    Name: linux-azure

    Purl: pkg:deb/ubuntu/linux-azure?arch=source&distro=trusty%2Fesm

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -4.15.0-1098.109~14.04.1

    Affected versions

    4.15.0-1023.24~14.04.1
    4.15.0-1030.31~14.04.1
    4.15.0-1031.32~14.04.1
    4.15.0-1032.33~14.04.2
    4.15.0-1035.36~14.04.2
    4.15.0-1036.38~14.04.2
    4.15.0-1037.39~14.04.2
    4.15.0-1039.41~14.04.2
    4.15.0-1040.44~14.04.1
    4.15.0-1041.45~14.04.1
    4.15.0-1042.46~14.04.1
    4.15.0-1045.49~14.04.1
    4.15.0-1046.50~14.04.1
    4.15.0-1047.51~14.04.1
    4.15.0-1049.54~14.04.1
    4.15.0-1050.55~14.04.1
    4.15.0-1051.56~14.04.1
    4.15.0-1052.57~14.04.1
    4.15.0-1055.60~14.04.1
    4.15.0-1056.61~14.04.1
    4.15.0-1057.62~14.04.1
    4.15.0-1059.64~14.04.1
    4.15.0-1060.65~14.04.1
    4.15.0-1061.66~14.04.1
    4.15.0-1063.68~14.04.1
    4.15.0-1064.69~14.04.1
    4.15.0-1066.71~14.04.1
    4.15.0-1067.72~14.04.1
    4.15.0-1069.74~14.04.1
    4.15.0-1071.76~14.04.1
    4.15.0-1074.79~14.04.1
    4.15.0-1077.82~14.04.1
    4.15.0-1082.92~14.04.1
    4.15.0-1083.93~14.04.1
    4.15.0-1089.99~14.04.1
    4.15.0-1091.101~14.04.1
    4.15.0-1092.102~14.04.1
    4.15.0-1093.103~14.04.1
    4.15.0-1095.105~14.04.1
    4.15.0-1096.106~14.04.1

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High