low 3.3

CVE-2021-3655 json

A vulnerability was found in the Linux kernel in versions prior to v5.14-rc1.

published 2021-08-05 5 y ago modified 2026-10-08 31 d ago also EUVD-2021-26950

cvss: 3.3; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 23%
public exploits: 0; none known

A vulnerability was found in the Linux kernel in versions prior to v5.14-rc1. Missing size validations on inbound SCTP packets may allow the kernel to read uninitialized memory.

Patch / fix

fixed in 1 distros 6 links 1

linux linux_kernel 5.14

debian ubuntu suse opensuse azure linux arch linux

linux Debian 14, Debian 13, Debian 12 5.10.46-3

debian advisories DEBIAN-CVE-2021-3655

linux Ubuntu 18.04 LTS 4.15.0-162.170
linux Ubuntu 20.04 LTS 5.4.0-91.102
linux-aws Ubuntu 18.04 LTS 4.15.0-1115.122
linux-aws Ubuntu 20.04 LTS 5.4.0-1060.63
linux-gcp Ubuntu 20.04 LTS 5.4.0-1058.62
linux-gke Ubuntu 20.04 LTS 5.4.0-1056.59
linux-ibm Ubuntu 20.04 LTS 5.4.0-1008.9
linux-kvm Ubuntu 18.04 LTS 4.15.0-1102.104

ubuntu advisories UBUNTU-CVE-2021-3655

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

kernel-syms SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.12.14-95.83.2
kernel-source SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.12.14-95.83.2
kernel-default SLES for SAP 12 SP4, SLES 12 SP4-LTSS, SLE Live Patching 12 SP4 +3 more 4.12.14-95.83.2
kernel-syms SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.12.14-150.78.1
kernel-source SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.12.14-150.78.1
kernel-default SLES for SAP 15, SLES 15-LTSS, SLE Live Patching 15 +3 more 4.12.14-150.78.1
kernel-vanilla SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.12.14-150.78.1
kernel-obs-build SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.12.14-150.78.2

suse advisories SUSE-SU-2021:3972-1 SUSE-SU-2021:3969-1 SUSE-SU-2021:3935-1 SUSE-SU-2021:3929-1 SUSE-SU-2021:3876-1 SUSE-SU-2021:14849-1

kernel-default openSUSE Leap 15.3 4.12.14-197.102.2
kernel-vanilla openSUSE Leap 15.3 4.12.14-197.102.2
kernel-kvmsmall openSUSE Leap 15.3 4.12.14-197.102.2
kernel-zfcpdump openSUSE Leap 15.3 4.12.14-197.102.2
dtb-aarch64 openSUSE Leap 15.3 5.3.18-59.34.1
kernel-64kb openSUSE Leap 15.3 5.3.18-59.34.1
kernel-syms openSUSE Leap 15.3 5.3.18-59.34.1
kernel-obs-qa openSUSE Leap 15.3 5.3.18-59.34.1

opensuse advisories openSUSE-SU-2021:3876-1 openSUSE-SU-2021:3675-1 openSUSE-SU-2021:1477-1 openSUSE-SU-2021:3641-1

kernel CBL-Mariner 2.0 5.10.78.1-1

azure linux advisories AZL-6576

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

linux Arch Linux 5.13.4.arch1-1
linux-zen Arch Linux 5.13.4.zen1-1
linux-hardened Arch Linux 5.12.18.hardened1-1
linux-lts Arch Linux 5.10.51-1

arch linux advisories AVG-2181 AVG-2182 AVG-2228 AVG-2229

bugzilla.redhat.com/show_bug.cgi?id=1984024 advisory

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-3655 updated 2026-11-08 cvss 3.3

kernel: missing size validations on inbound SCTP packets

Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, kernel-alt, python-perf, +9 more
affected: workaround, no fix planned “Out of support scope”
Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
affected: workaround, no fix available
Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +82 more
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 31 d ago (2026-10-08)

Exploit prediction

0.31% chance of exploitation in the next 30 days, higher than 23% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	3.3	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
NVD	2.0	2.1	AV:L/AC:L/Au:N/C:P/I:N/A:N

Affected products

n/a kernel

Classification

Weakness

CWE-909 Missing Initialization of Resource
CWE-20 Improper Input Validation

Technology feeds

Linux kernel rss critical rss

References

bugzilla.redhat.com /show_bug.cgi?id=1984024
issue-tracking, patch, third-party-advisory
lists.debian.org /debian-lts-announce/2021/10/msg00010.html
mailing-list, third-party-advisory
lists.debian.org /debian-lts-announce/2021/12/msg00012.html
mailing-list, third-party-advisory

Sources

CVE List CVE-2021-3655
NVD CVE-2021-3655

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary