01 Record

CVE-2021-33909

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

UnratedPUBLISHEDCNA: mitre

CNA base scoreUnratedNo CNA CVSS vector

View raw JSON

02 Description

03 Exploitation and scoring

Exploitation: Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.
SSVC decision: Not assessed by CISA
EPSS probability: 9.72% probability of exploitation activity in the next 30 days.
EPSS percentile: Equal to or higher than the score of 95.0% of scored records. A rank, not a probability.
NVD base score: 7.8 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD analysis status: Modified. NVD last modified this record on 2026-06-17.
Red Hat severity: Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published

2021-07-20 18:01Z5 YR AGO

Last updated

2024-08-04 00:05Z2 YR AGO

Reserved

2021-06-07

Assigning CNA

mitre

Record state

PUBLISHED

Severity

Not rated by the issuing CNA

CNA CVSS vector

Not published by the issuing CNA

Weaknesses

CWE-190Integer Overflow or WraparoundBase
CWE-787Out-of-bounds WriteBase

Data version

5.1

Document digest

569ed0ed47197a97074074c33419aa37b3b1f22e5ef3468c232ba0705ee23745

05 Affected products

VendorProductVersionsPlatforms

debiandebian_linuxNot specified—

fedoraprojectfedoraNot specified—

linuxlinux_kernelNot specified—

netapphci_management_nodeNot specified—

netappsolidfireNot specified—

oraclecommunications_session_border_controllerNot specified—

redhatenterprise_linuxNot specified—

redhatrhel_ausNot specified—

redhatrhel_e4sNot specified—

redhatrhel_elsNot specified—

redhatrhel_eusNot specified—

redhatrhel_extras_rtNot specified—

redhatrhel_tusNot specified—

redhatrhev_hypervisorNot specified—

sonicwallsma1000Not specified—

sonicwallsma1000_firmwareNot specified—

06 References

lists.debian.org[debian-lts-announce] 20210720 [SECURITY] [DLA 2713-2] linux security updatehttps://lists.debian.org/debian-lts-announce/2021/07/msg00016.htmlmailing-listx_refsource_MLIST
lists.debian.org[debian-lts-announce] 20210720 [SECURITY] [DLA 2713-1] linux security updatehttps://lists.debian.org/debian-lts-announce/2021/07/msg00014.htmlmailing-listx_refsource_MLIST
lists.debian.org[debian-lts-announce] 20210720 [SECURITY] [DLA 2714-1] linux-4.19 security updatehttps://lists.debian.org/debian-lts-announce/2021/07/msg00015.htmlmailing-listx_refsource_MLIST
www.debian.orgDSA-4941https://www.debian.org/security/2021/dsa-4941vendor-advisoryx_refsource_DEBIAN
lists.fedoraproject.orgFEDORA-2021-07dc0b3eb1https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z4UHHIGISO3FVRF4CQNJS4IKA25ATSFU/vendor-advisoryx_refsource_FEDORA
www.openwall.com[oss-security] 20210722 Re: CVE-2021-33909: size_t-to-int vulnerability in Linux's filesystem layerhttp://www.openwall.com/lists/oss-security/2021/07/22/7mailing-listx_refsource_MLIST
www.openwall.com[oss-security] 20210825 Re: CVE-2021-33909: size_t-to-int vulnerability in Linux's filesystem layerhttp://www.openwall.com/lists/oss-security/2021/08/25/10mailing-listx_refsource_MLIST
www.openwall.com[oss-security] 20210916 Containers-optimized OS (COS) membership in the linux-distros listhttp://www.openwall.com/lists/oss-security/2021/09/17/2mailing-listx_refsource_MLIST
www.openwall.com[oss-security] 20210917 Re: Containers-optimized OS (COS) membership in the linux-distros listhttp://www.openwall.com/lists/oss-security/2021/09/17/4mailing-listx_refsource_MLIST
www.openwall.com[oss-security] 20210920 Re: Containers-optimized OS (COS) membership in the linux-distros listhttp://www.openwall.com/lists/oss-security/2021/09/21/1mailing-listx_refsource_MLIST
www.oracle.comhttps://www.oracle.com/security-alerts/cpujan2022.htmlx_refsource_MISC
www.openwall.comhttps://www.openwall.com/lists/oss-security/2021/07/20/1x_refsource_MISC
github.comhttps://github.com/torvalds/linux/commit/8cae8cd89f05f6de223d63e6d15e31c8ba9cf53bx_refsource_CONFIRM
cdn.kernel.orghttps://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.13.4x_refsource_CONFIRM
packetstormsecurity.comhttp://packetstormsecurity.com/files/163621/Sequoia-A-Deep-Root-In-Linuxs-Filesystem-Layer.htmlx_refsource_MISC
packetstormsecurity.comhttp://packetstormsecurity.com/files/163671/Kernel-Live-Patch-Security-Notice-LSN-0079-1.htmlx_refsource_MISC
security.netapp.comhttps://security.netapp.com/advisory/ntap-20210819-0004/x_refsource_CONFIRM
packetstormsecurity.comhttp://packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.htmlx_refsource_MISC
packetstormsecurity.comhttp://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.htmlx_refsource_MISC
psirt.global.sonicwall.comhttps://psirt.global.sonicwall.com/vuln-detail/SNWLID-2022-0015x_refsource_CONFIRM

07 Fixed in

AlmaLinux 8

kernel-tools-libs-devel
Fixed in 4.18.0-305.10.2.el8_4

Arch Linux

linux
Fixed in 5.13.4.arch1-1
linux-hardened
Fixed in 5.12.19.hardened1-1
linux-lts
Fixed in 5.10.52-1
linux-zen
Fixed in 5.13.4.zen1-1

Source: Arch Linux Security Tracker, the Arch Linux security team. Reformatted by exploit.cc.

CloudLinux 8

kernel-tools-libs-devel
Fixed in 4.18.0-305.10.2.el8_4

Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.

Debian 12

linux
Fixed in 5.10.46-2

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

linux
Fixed in 5.10.46-2

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

linux
Fixed in 5.10.46-2

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.