CVE-2021-33909

Description

fs/seq_file.c in the Linux kernel 3.16 through 5.13.x before 5.13.4 does not properly restrict seq buffer allocations, leading to an integer overflow, an Out-of-bounds Write, and escalation to root by an unprivileged user, aka CID-8cae8cd89f05.

CVSS Metrics

• v3.1•HIGH•Score: 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• v2.0•HIGH•Score: 7.2AV:L/AC:L/Au:N/C:C/I:C/A:C

EPSS Trends

Current EPSS score: 9.73%• Percentile: 95%

Techniques & Countermeasures

• CWE-190•Integer Overflow or Wraparound

  The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

• CWE-787•Out-of-bounds Write

  The product writes data past the end, or before the beginning, of the intended buffer.

Affected Systems

• debian•linux

  < 5.10.46-2 | < 5.10.46-2 | < 5.10.46-2 | < 5.10.46-2

• ubuntu•linux

  < 3.13.0-186.237 | < 4.4.0-212.244 | < 4.15.0-151.157 | < 5.4.0-80.90

• ubuntu•linux-aws

  < 4.4.0-1094.99 | < 4.4.0-1130.144 | < 4.15.0-1109.116 | < 5.4.0-1054.57

• ubuntu•linux-aws-5.0

  all

• ubuntu•linux-aws-5.11

  < 5.11.0-1014.15~20.04.1

• ubuntu•linux-aws-5.3

  all

• ubuntu•linux-aws-5.4

  < 5.4.0-1054.57~18.04.1

• ubuntu•linux-aws-5.8

  < 5.8.0-1041.43~20.04.1

• ubuntu•linux-aws-fips

  < 4.15.0-2051.53 | all | < 5.4.0-1069.73+fips2

• ubuntu•linux-aws-hwe

  < 4.15.0-1109.116~16.04.1

• ubuntu•linux-azure

  < 4.15.0-1121.134~14.04.1 | < 4.15.0-1121.134~16.04.1 | all | < 5.4.0-1055.57

• ubuntu•linux-azure-4.15

  < 4.15.0-1121.134

• ubuntu•linux-azure-5.11

  < 5.11.0-1012.13~20.04.1

• ubuntu•linux-azure-5.3

  all

• ubuntu•linux-azure-5.4

  < 5.4.0-1055.57~18.04.1

• ubuntu•linux-azure-5.8

  < 5.8.0-1039.42~20.04.1

• ubuntu•linux-azure-edge

  all

• ubuntu•linux-azure-fips

  < 4.15.0-2033.37 | all | < 5.4.0-1073.76+fips1

• ubuntu•linux-bluefield

  all | < 5.4.0-1016.19

• ubuntu•linux-dell300x

  < 4.15.0-1027.32

• ubuntu•linux-fips

  < 4.4.0-1064.70 | all | < 4.15.0-1066.75 | < 5.4.0-1031.36

• ubuntu•linux-gcp

  < 4.15.0-1106.120~16.04.1 | all | < 5.4.0-1049.53

• ubuntu•linux-gcp-4.15

  < 4.15.0-1106.120

• ubuntu•linux-gcp-5.11

  < 5.11.0-1014.16~20.04.1

• ubuntu•linux-gcp-5.3

  all

• ubuntu•linux-gcp-5.4

  < 5.4.0-1049.53~18.04.1

• ubuntu•linux-gcp-5.8

  < 5.8.0-1038.40~20.04.1

• ubuntu•linux-gcp-edge

  all

• ubuntu•linux-gcp-fips

  < 4.15.0-2016.18 | all | < 5.4.0-1067.71~20.04.1

• ubuntu•linux-gke

  < 5.4.0-1049.52

• ubuntu•linux-gke-4.15

  all

• ubuntu•linux-gke-5.3

  < 5.3.0-1045.48

• ubuntu•linux-gke-5.4

  < 5.4.0-1049.52~18.04.1

• ubuntu•linux-gkeop

  < 5.4.0-1021.22

• ubuntu•linux-gkeop-5.4

  < 5.4.0-1021.22~18.04.1

• ubuntu•linux-hwe

  < 4.15.0-151.157~16.04.1 | < 5.3.0-76.72

• ubuntu•linux-hwe-5.11

  < 5.11.0-25.27~20.04.1

• ubuntu•linux-hwe-5.4

  < 5.4.0-80.90~18.04.1

• ubuntu•linux-hwe-5.8

  < 5.8.0-63.71~20.04.1

• ubuntu•linux-hwe-edge

  all | all

• ubuntu•linux-intel-iot-realtime

  all

• ubuntu•linux-kvm

  < 4.4.0-1095.104 | < 4.15.0-1097.99 | < 5.4.0-1044.46

• ubuntu•linux-lts-xenial

  < 4.4.0-212.244~14.04.1

• ubuntu•linux-oem

  all

• ubuntu•linux-oem-5.10

  < 5.10.0-1038.40

• ubuntu•linux-oem-5.6

  all

• ubuntu•linux-oracle

  < 4.15.0-1078.86~16.04.1 | < 4.15.0-1078.86 | < 5.4.0-1052.56

• ubuntu•linux-oracle-5.0

  all

• ubuntu•linux-oracle-5.11

  < 5.11.0-1013.14~20.04.1

• ubuntu•linux-oracle-5.3

  all

Showing first 50 affected entries in server-rendered view.

References (39)

• https://lists.debian.org/debian-lts-announce/2021/07/msg00016.html
• https://lists.debian.org/debian-lts-announce/2021/07/msg00014.html
• https://lists.debian.org/debian-lts-announce/2021/07/msg00015.html
• https://www.debian.org/security/2021/dsa-4941
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z4UHHIGISO3FVRF4CQNJS4IKA25ATSFU/
• http://www.openwall.com/lists/oss-security/2021/07/22/7
• http://www.openwall.com/lists/oss-security/2021/08/25/10
• http://www.openwall.com/lists/oss-security/2021/09/17/2
• http://www.openwall.com/lists/oss-security/2021/09/17/4
• http://www.openwall.com/lists/oss-security/2021/09/21/1
• https://www.oracle.com/security-alerts/cpujan2022.html
• https://www.openwall.com/lists/oss-security/2021/07/20/1
• https://github.com/torvalds/linux/commit/8cae8cd89f05f6de223d63e6d15e31c8ba9cf53b
• https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.13.4
• http://packetstormsecurity.com/files/163621/Sequoia-A-Deep-Root-In-Linuxs-Filesystem-Layer.html
• http://packetstormsecurity.com/files/163671/Kernel-Live-Patch-Security-Notice-LSN-0079-1.html
• https://security.netapp.com/advisory/ntap-20210819-0004/
• http://packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.html
• http://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.html
• https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2022-0015
• https://access.redhat.com/errata/RHSA-2021:2722
• https://access.redhat.com/security/updates/classification/#important
• https://access.redhat.com/security/vulnerabilities/RHSB-2021-006
• https://bugzilla.redhat.com/show_bug.cgi?id=1970273
• https://security.access.redhat.com/data/csaf/v2/advisories/2021/rhsa-2021_2722.json
• https://access.redhat.com/security/cve/CVE-2021-33909
• https://www.cve.org/CVERecord?id=CVE-2021-33909
• https://nvd.nist.gov/vuln/detail/CVE-2021-33909
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8cae8cd89f05f6de223d63e6d15e31c8ba9cf53b
• https://www.qualys.com/2021/07/20/cve-2021-33909/sequoia-local-privilege-escalation-linux.txt
• https://access.redhat.com/errata/RHSA-2021:2723
• https://security.access.redhat.com/data/csaf/v2/advisories/2021/rhsa-2021_2723.json
• https://ubuntu.com/security/CVE-2021-33909
• https://ubuntu.com/security/notices/USN-5018-1
• https://ubuntu.com/security/notices/USN-5017-1
• https://ubuntu.com/security/notices/USN-5016-1
• https://ubuntu.com/security/notices/USN-5015-1
• https://ubuntu.com/security/notices/USN-5014-1
• https://security-tracker.debian.org/tracker/CVE-2021-33909