Incorrect authorization in Linux kernel - CVE-2021-3493

Vulnerability identifier: #VU92413

CSH Severity: Low

CVSS v4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2021-3493

CWE-ID: CWE-863

Exploitation vector: Local access

Exploit availability: The vulnerability is being exploited in the wild

The vulnerability allows a local user to execute arbitrary code.

The vulnerability exists due to incorrect authorization error within the validheader() and cap_convert_nscap() functions in security/commoncap.c, within the vfs_setxattr() and setxattr() functions in fs/xattr.c. A local user can execute arbitrary code.

Linux kernel
Ubuntu
linux-image-powerpc-smp-lts-xenial (Ubuntu package)
linux-image-virtual-lts-xenial (Ubuntu package)
linux-image-powerpc64-smp-lts-xenial (Ubuntu package)
linux-image-powerpc64-emb-lts-xenial (Ubuntu package)
linux-image-generic-lpae-lts-xenial (Ubuntu package)
linux-image-lowlatency-lts-xenial (Ubuntu package)
linux-image-generic-lts-xenial (Ubuntu package)
linux-image-powerpc-e500mc-lts-xenial (Ubuntu package)
linux-image-generic (Ubuntu package)
linux-image-generic-lpae (Ubuntu package)
linux-image-lowlatency (Ubuntu package)
linux-image-virtual (Ubuntu package)
linux-image-powerpc-e500mc (Ubuntu package)
linux-image-powerpc-smp (Ubuntu package)
linux-image-powerpc64-emb (Ubuntu package)
linux-image-powerpc64-smp (Ubuntu package)
linux-image-4.4.0-209-powerpc64-smp (Ubuntu package)
linux-image-4.4.0-209-powerpc64-emb (Ubuntu package)
linux-image-4.4.0-209-powerpc-smp (Ubuntu package)
linux-image-4.4.0-209-powerpc-e500mc (Ubuntu package)
linux-image-4.4.0-209-lowlatency (Ubuntu package)
linux-image-4.4.0-209-generic-lpae (Ubuntu package)
linux-image-4.4.0-209-generic (Ubuntu package)
linux-image-4.4.0-210-generic-lpae (Ubuntu package)
linux-image-4.4.0-210-lowlatency (Ubuntu package)
linux-image-4.4.0-210-powerpc-e500mc (Ubuntu package)
linux-image-4.4.0-210-powerpc64-smp (Ubuntu package)
linux-image-4.4.0-210-generic (Ubuntu package)
linux-image-4.4.0-210-powerpc-smp (Ubuntu package)
linux-image-4.4.0-210-powerpc64-emb (Ubuntu package)
linux-image-aws (Ubuntu package)
linux-image-4.4.0-1091-aws (Ubuntu package)
linux-image-kvm (Ubuntu package)
linux-image-4.4.0-1092-aws (Ubuntu package)
linux-image-4.4.0-1092-kvm (Ubuntu package)
linux-image-4.4.0-1093-kvm (Ubuntu package)
linux-image-4.4.0-1127-aws (Ubuntu package)
linux-image-4.4.0-1128-aws (Ubuntu package)
linux-image-raspi2 (Ubuntu package)
linux-image-4.4.0-1151-raspi2 (Ubuntu package)
linux-image-4.4.0-1152-raspi2 (Ubuntu package)
linux-image-snapdragon (Ubuntu package)
linux-image-4.4.0-1155-snapdragon (Ubuntu package)
linux-image-4.4.0-1156-snapdragon (Ubuntu package)
linux-image-oem (Ubuntu package)
linux-image-virtual-hwe-16.04 (Ubuntu package)
linux-image-generic-hwe-16.04 (Ubuntu package)
linux-image-lowlatency-hwe-16.04 (Ubuntu package)
linux-image-generic-lpae-hwe-16.04 (Ubuntu package)
linux-image-4.15.0-142-generic (Ubuntu package)
linux-image-4.15.0-142-generic-lpae (Ubuntu package)
linux-image-4.15.0-142-lowlatency (Ubuntu package)
linux-image-dell300x (Ubuntu package)
linux-image-4.15.0-1017-dell300x (Ubuntu package)
linux-image-oracle (Ubuntu package)
linux-image-4.15.0-1070-oracle (Ubuntu package)
linux-image-oracle-lts-18.04 (Ubuntu package)
linux-image-4.15.0-1084-raspi2 (Ubuntu package)
linux-image-4.15.0-1090-kvm (Ubuntu package)
linux-image-gke (Ubuntu package)
linux-image-gcp (Ubuntu package)
linux-image-4.15.0-1098-gcp (Ubuntu package)
linux-image-gcp-lts-18.04 (Ubuntu package)
linux-image-aws-hwe (Ubuntu package)
linux-image-aws-lts-18.04 (Ubuntu package)
linux-image-4.15.0-1099-aws (Ubuntu package)
linux-image-4.15.0-1101-snapdragon (Ubuntu package)
linux-image-azure-lts-18.04 (Ubuntu package)
linux-image-azure (Ubuntu package)
linux-image-4.15.0-1113-azure (Ubuntu package)
linux-image-5.3.0-74-lowlatency (Ubuntu package)
linux-image-5.3.0-74-generic (Ubuntu package)
linux-image-gkeop-5.3 (Ubuntu package)
linux-image-raspi2-hwe-18.04 (Ubuntu package)
linux-image-5.3.0-1040-raspi2 (Ubuntu package)
linux-image-gke-5.3 (Ubuntu package)
linux-image-5.3.0-1043-gke (Ubuntu package)
linux-image-oem-20.04 (Ubuntu package)
linux-image-5.6.0-1055-oem (Ubuntu package)

Install update from vendor's repository.

linux-image-powerpc-smp-lts-xenial (Ubuntu package) - addressed in versions 4.4.0.209.182, 4.4.0.210.183
linux-image-virtual-lts-xenial (Ubuntu package) - addressed in versions 4.4.0.209.182, 4.4.0.210.183
linux-image-powerpc64-smp-lts-xenial (Ubuntu package) - addressed in versions 4.4.0.209.182, 4.4.0.210.183
linux-image-powerpc64-emb-lts-xenial (Ubuntu package) - addressed in versions 4.4.0.209.182, 4.4.0.210.183
linux-image-generic-lpae-lts-xenial (Ubuntu package) - addressed in versions 4.4.0.209.182, 4.4.0.210.183
linux-image-lowlatency-lts-xenial (Ubuntu package) - addressed in versions 4.4.0.209.182, 4.4.0.210.183
linux-image-generic-lts-xenial (Ubuntu package) - addressed in versions 4.4.0.209.182, 4.4.0.210.183
linux-image-powerpc-e500mc-lts-xenial (Ubuntu package) - addressed in versions 4.4.0.209.182, 4.4.0.210.183
linux-image-generic (Ubuntu package) - addressed in versions 4.4.0.209.215, 4.4.0.210.216, 4.15.0.142.129
linux-image-generic-lpae (Ubuntu package) - addressed in versions 4.4.0.209.215, 4.4.0.210.216, 4.15.0.142.129
linux-image-lowlatency (Ubuntu package) - addressed in versions 4.4.0.209.215, 4.4.0.210.216, 4.15.0.142.129
linux-image-virtual (Ubuntu package) - addressed in versions 4.4.0.209.215, 4.4.0.210.216, 4.15.0.142.129
linux-image-powerpc-e500mc (Ubuntu package) - addressed in versions 4.4.0.209.215, 4.4.0.210.216
linux-image-powerpc-smp (Ubuntu package) - addressed in versions 4.4.0.209.215, 4.4.0.210.216
linux-image-powerpc64-emb (Ubuntu package) - addressed in versions 4.4.0.209.215, 4.4.0.210.216
linux-image-powerpc64-smp (Ubuntu package) - addressed in versions 4.4.0.209.215, 4.4.0.210.216
linux-image-4.4.0-209-powerpc64-smp (Ubuntu package) - update to 4.4.0-209.241~14.04.1
linux-image-4.4.0-209-powerpc64-emb (Ubuntu package) - update to 4.4.0-209.241~14.04.1
linux-image-4.4.0-209-powerpc-smp (Ubuntu package) - update to 4.4.0-209.241~14.04.1
linux-image-4.4.0-209-powerpc-e500mc (Ubuntu package) - update to 4.4.0-209.241~14.04.1
linux-image-4.4.0-209-lowlatency (Ubuntu package) - update to 4.4.0-209.241~14.04.1
linux-image-4.4.0-209-generic-lpae (Ubuntu package) - update to 4.4.0-209.241~14.04.1
linux-image-4.4.0-209-generic (Ubuntu package) - update to 4.4.0-209.241~14.04.1
linux-image-4.4.0-210-generic-lpae (Ubuntu package) - update to 4.4.0-210.242~14.04.1
linux-image-4.4.0-210-lowlatency (Ubuntu package) - update to 4.4.0-210.242~14.04.1
linux-image-4.4.0-210-powerpc-e500mc (Ubuntu package) - update to 4.4.0-210.242~14.04.1
linux-image-4.4.0-210-powerpc64-smp (Ubuntu package) - update to 4.4.0-210.242~14.04.1
linux-image-4.4.0-210-generic (Ubuntu package) - update to 4.4.0-210.242~14.04.1
linux-image-4.4.0-210-powerpc-smp (Ubuntu package) - update to 4.4.0-210.242~14.04.1
linux-image-4.4.0-210-powerpc64-emb (Ubuntu package) - update to 4.4.0-210.242~14.04.1
linux-image-aws (Ubuntu package) - addressed in versions 4.4.0.1091.88, 4.4.0.1092.89, 4.4.0.1127.132, 4.4.0.1128.133
linux-image-4.4.0-1091-aws (Ubuntu package) - update to 4.4.0-1091.95
linux-image-kvm (Ubuntu package) - addressed in versions 4.4.0.1092.90, 4.4.0.1093.91, 4.15.0.1090.86
linux-image-4.4.0-1092-aws (Ubuntu package) - update to 4.4.0-1092.96
linux-image-4.4.0-1092-kvm (Ubuntu package) - update to 4.4.0-1092.101
linux-image-4.4.0-1093-kvm (Ubuntu package) - update to 4.4.0-1093.102
linux-image-4.4.0-1127-aws (Ubuntu package) - update to 4.4.0-1127.141
linux-image-4.4.0-1128-aws (Ubuntu package) - update to 4.4.0-1128.142
linux-image-raspi2 (Ubuntu package) - addressed in versions 4.4.0.1151.151, 4.4.0.1152.152, 4.15.0.1084.81
linux-image-4.4.0-1151-raspi2 (Ubuntu package) - update to 4.4.0-1151.162
linux-image-4.4.0-1152-raspi2 (Ubuntu package) - update to 4.4.0-1152.163
linux-image-snapdragon (Ubuntu package) - addressed in versions 4.4.0.1155.147, 4.4.0.1156.148, 4.15.0.1101.104
linux-image-4.4.0-1155-snapdragon (Ubuntu package) - update to 4.4.0-1155.165
linux-image-4.4.0-1156-snapdragon (Ubuntu package) - update to 4.4.0-1156.166
linux-image-oem (Ubuntu package) - update to 4.15.0.142.137
linux-image-virtual-hwe-16.04 (Ubuntu package) - update to 4.15.0.142.137
linux-image-generic-hwe-16.04 (Ubuntu package) - update to 4.15.0.142.137
linux-image-lowlatency-hwe-16.04 (Ubuntu package) - update to 4.15.0.142.137
linux-image-generic-lpae-hwe-16.04 (Ubuntu package) - update to 4.15.0.142.137
linux-image-4.15.0-142-generic (Ubuntu package) - addressed in versions 4.15.0-142.146, 4.15.0-142.146~16.04.1
linux-image-4.15.0-142-generic-lpae (Ubuntu package) - addressed in versions 4.15.0-142.146, 4.15.0-142.146~16.04.1
linux-image-4.15.0-142-lowlatency (Ubuntu package) - addressed in versions 4.15.0-142.146, 4.15.0-142.146~16.04.1
linux-image-dell300x (Ubuntu package) - update to 4.15.0.1017.19
linux-image-4.15.0-1017-dell300x (Ubuntu package) - update to 4.15.0-1017.21
linux-image-oracle (Ubuntu package) - update to 4.15.0.1070.58
linux-image-4.15.0-1070-oracle (Ubuntu package) - addressed in versions 4.15.0-1070.78, 4.15.0-1070.78~16.04.1
linux-image-oracle-lts-18.04 (Ubuntu package) - update to 4.15.0.1070.80
linux-image-4.15.0-1084-raspi2 (Ubuntu package) - update to 4.15.0-1084.89
linux-image-4.15.0-1090-kvm (Ubuntu package) - update to 4.15.0-1090.92
linux-image-gke (Ubuntu package) - update to 4.15.0.1098.99
linux-image-gcp (Ubuntu package) - update to 4.15.0.1098.99
linux-image-4.15.0-1098-gcp (Ubuntu package) - addressed in versions 4.15.0-1098.111, 4.15.0-1098.111~16.04.1
linux-image-gcp-lts-18.04 (Ubuntu package) - update to 4.15.0.1098.116
linux-image-aws-hwe (Ubuntu package) - update to 4.15.0.1099.92
linux-image-aws-lts-18.04 (Ubuntu package) - update to 4.15.0.1099.102
linux-image-4.15.0-1099-aws (Ubuntu package) - addressed in versions 4.15.0-1099.106, 4.15.0-1099.106~16.04.1
linux-image-4.15.0-1101-snapdragon (Ubuntu package) - update to 4.15.0-1101.110
linux-image-azure-lts-18.04 (Ubuntu package) - update to 4.15.0.1113.86
linux-image-azure (Ubuntu package) - addressed in versions 4.15.0.1113.86, 4.15.0.1113.104
linux-image-4.15.0-1113-azure (Ubuntu package) - addressed in versions 4.15.0-1113.126~14.04.1, 4.15.0-1113.126~16.04.1
linux-image-5.3.0-74-lowlatency (Ubuntu package) - update to 5.3.0-74.70
linux-image-5.3.0-74-generic (Ubuntu package) - update to 5.3.0-74.70
linux-image-gkeop-5.3 (Ubuntu package) - update to 5.3.0.74.131
linux-image-raspi2-hwe-18.04 (Ubuntu package) - update to 5.3.0.1040.29
linux-image-5.3.0-1040-raspi2 (Ubuntu package) - update to 5.3.0-1040.42
linux-image-gke-5.3 (Ubuntu package) - update to 5.3.0.1043.26
linux-image-5.3.0-1043-gke (Ubuntu package) - update to 5.3.0-1043.46
linux-image-oem-20.04 (Ubuntu package) - update to 5.6.0.1055.51
linux-image-5.6.0-1055-oem (Ubuntu package) - update to 5.6.0-1055.59

• Exploit #10117 - CVE-2021-3493 (Ubuntu OverlayFS Local Privesc) (June 21, 2024)
• Exploit #10006 - 2021 Ubuntu Overlayfs LPE (June 20, 2024)

• https://www.openwall.com/lists/oss-security/2021/04/16/1
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52
• https://ubuntu.com/security/notices/USN-4917-1
• http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html
• http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html
• http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.html

• Incorrect authorization in Linux kernel fs
• Ubuntu update for linux
• Ubuntu update for linux