CVE-2021-33909

highpriority · track · 44EPSS 0.097 · 95 %ileexploit · PoCDEEURUUS

grimoire priorityP1 · Urgent

Exploitable?

Public exploit

4 exploits · PoC

Likely / severe?

9.73% (95th) EPSS

CVSS 7.2 · high

Is it mine?

76 products

Check your exposure

Who says so?

7 sources

cnnvd · enisa_euvd · fstec_bdu · osv

EPSS · scored 2026-10-26

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.

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

FixedSIMATIC RF160B (6GT2003-0FA00)siemens_psirt
Update to V2.2 or later version
MitigationSIMATIC RF160B (6GT2003-0FA00)cisa_csaf_ot
Siemens has released a new version (V2.2) for SIMATIC RF160B and recommends to update to the latest version.

cvss

Technical severity, 0–10. One row per scoring source.

7.8

010

base score 0–10 · higher = more severe · hover a vector to decode

v2.07.2highAV:L/AC:L/Au:N/C:C/I:C/A:Cprimary · NVD / NIST USexploitability 3.9 · impact 10

v3.17.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 1.8 · impact 5.9

v3.17.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · CISA US

v3.17.8highAV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU

v3.17.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:Csecondary · Siemens ProductCERT DE

v3.17.4highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:Psecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-190USprimaryCWE-787USprimaryCWE-190USCWE-190USCWE-190USCWE-787US

exploits (4)

Public proof-of-concept and weaponised exploit code.

ChrisTheCoolHut/CVE-2021-33909CVE-2021-33909 SequoiaPoC · poc_in_github
Liang2580/CVE-2021-33909Sequoia exploit (7/20/21)PoC · poc_in_github
baerwolf/cve-2021-33909This module fixes an issue in the kernels filesystem layer (CVE-2021-33909) by kprobe-replacing vulnerable functions during runtimePoC · poc_in_github
bbinfosec43/CVE-2021-33909Exploit code for CVE-2021-33909,Just a dump of removed https://github.com/AmIAHuman/ repoPoC · poc_in_github

affected products (76)

Products and version ranges known to be affected.

Amazon Linux 2all versionscert_bundDEcpe:/o:amazon:linux_2:-
Avaya Aura Experience Portalall versionscert_bundDEcpe:/a:avaya:aura_experience_portal:-
Avaya Breeze Platformall versionscert_bundDEcpe:/a:avaya:breeze_platform:-
Avaya Session Border Controllerall versionscert_bundDEcpe:/h:avaya:session_border_controller:-
Avaya one-Xall versionscert_bundDEcpe:/a:avaya:one-x:-
Extreme Networks Extreme Management Centerall versionscert_bundDEcpe:/a:extremenetworks:netsight:-
Extreme Networks ExtremeXOSall versionscert_bundDEcpe:/o:extremenetworks:extremexos:-
F5 BIG-IPall versionscert_bundDEcpe:/a:f5:big-ip:-
IGEL OSall versionscert_bundDEcpe:/o:igel:os:-
Meinberg LANTIME <6.24.029all versionscert_bundDE
Meinberg LANTIME <7.04.008all versionscert_bundDE
NetApp AFF Baseboard Management Controllerall versionscert_bundDEcpe:/h:netapp:aff:::baseboard_management_controller
NetApp FAS Baseboard Management Controllerall versionscert_bundDEcpe:/h:netapp:fas:baseboard_management_controller
Open Source Arch Linuxall versionscert_bundDEcpe:/o:archlinux:archlinux:-
Open Source Linux Kernel <5.13.4all versionscert_bundDE
Oracle Linuxall versionscert_bundDEcpe:/o:oracle:linux:-
Red Hat Enterprise Linuxall versionscert_bundDEcpe:/o:redhat:enterprise_linux:-
SUSE Linuxall versionscert_bundDEcpe:/o:suse:suse_linux:-
SonicWall SMA <12.4.2-05082all versionscert_bundDE
Ubuntu Linuxall versionscert_bundDEcpe:/o:canonical:ubuntu_linux:-

showing 20 of 76

advisories (6)

Vendor and ecosystem advisories describing this.

SSA-770721SSA-770721: Multiple Vulnerabilities in SIMATIC RF160B before V2.22024-03-12csaf · siemens_psirtDE
SIMATIC RF160B contain multiple vulnerabilities of different types that could allow an attacker to execute arbitrary code within the context of a privileged process. Siemens has released a new version for SIMATIC RF160B and recommends to update to the latest version.
WID-SEC-W-2022-0965Linux Kernel: Schwachstelle ermöglicht PrivilegieneskalationDeutsch2021-07-20csaf · cert_bundDE
Ein lokaler Angreifer kann eine Schwachstelle im Linux Kernel, Red Hat Enterprise Linux und Ubuntu Linux ausnutzen, um seine Privilegien zu erhöhen.
WID-SEC-W-2023-0063Juniper Junos Space: Mehrere SchwachstellenDeutsch2022-01-12csaf · cert_bundDE
Ein Angreifer aus dem angrenzenden Netzwerk oder ein entfernter anonymer, authentisierter oder lokaler Angreifer kann mehrere Schwachstellen in Juniper Junos Space ausnutzen, um Sicherheitsmaßnahmen zu umgehen, vertrauliche Informationen offenzulegen, einen Denial-of-Service-Zustand auszulösen, beliebigen Code auszuführen und seine Privilegien zu erweitern.
WID-SEC-W-2024-1591Juniper JUNOS: Mehrere SchwachstellenDeutsch2024-07-10csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Juniper JUNOS ausnutzen, um einen Denial of Service zu verursachen, Informationen offenzulegen, Privilegien zu erweitern und Sicherheitsmechanismen inklusive zu umgehen.
ICSA-24-074-07Siemens SIMATIC2024-03-14icsa · cisa_csaf_otUS
Successful exploitation of these vulnerabilities could allow an attacker to execute arbitrary code within the context of a privileged process.
ASB-A-1950827502021-12-01vendor · osvUS
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.

also known as (5)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu osv cert_bund siemens_psirt cisa_csaf_ot NVD CVE.org MITRE

published 2021-07-20modified 2026-06-17

related (20,325)

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+20320 more

references (94)

External citations — patches, advisories, analysis.

scry

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