PatchTheCVECVE-2021-43267: An issue was discovered in net/tipc/crypto.c in the Linux kernel before 5.14.16
74
This week
CRITICAL 9.8REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE
CVE-2021-43267 is a critical-severity flaw (CVSS 9.8) affecting linux kernel, fedora, h300s firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
An issue was discovered in net/tipc/crypto.c in the Linux kernel before 5.14.16. The Transparent Inter-Process Communication (TIPC) functionality allows remote attackers to exploit insufficient validation of user-supplied sizes for the MSG_CRYPTO message type.
Why this priority
- Critical severity
- EPSS top 1%: very likely to be exploited
- Public exploit reference
- Remotely exploitable, no login, no user action
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 9.8 (Critical) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 57.9% (top 1%) |
| CISA exploited list | No |
| Weakness | CWE-1284 |
| Published | 2021-11-02 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
linux linux kernel UPGRADE
Affected: >= 5.10 and < 5.10.77 · >= 5.11 and < 5.14.16
Fixed in: 5.10.77, 5.14.16
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
fedoraproject fedora MITIGATE
Affected: 34 · 35
Fixed in: no fixed release known
Safe to downgrade to: a release before 34
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
netapp h300s firmware MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
netapp h500s firmware MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
netapp h700s firmware MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
netapp h300e firmware MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
Exact fixes by distribution
A distro patch exists: prefer upgrading over downgrading.
Fedora 46 · python-dtoc · FIXED · 0.1.0-1.fc46 · FEDORA-2026-e4734649a1 · source
sudo dnf upgrade --advisory=FEDORA-2026-e4734649a1
Fedora ELN · parallel · FIXED · 20261022-1.eln159 · FEDORA-2026-6d961c0286 · source
sudo dnf upgrade --advisory=FEDORA-2026-6d961c0286
Ubuntu 20.04 · linux · NOT AFFECTED
Ubuntu 22.04 · linux · NOT AFFECTED
Ubuntu 24.04 · linux · NOT AFFECTED
Ubuntu 22.04 · linux-allwinner-5.19 · NOT AFFECTED
Ubuntu 20.04 · linux-aws · NOT AFFECTED
Debian 12 · linux · FIXED · 5.14.16-1
sudo apt update && sudo apt install --only-upgrade linux
dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "5.14.16-1" && echo PATCHED || echo STILL-VULNERABLE
Debian 13 · linux · FIXED · 5.14.16-1
sudo apt update && sudo apt install --only-upgrade linux
dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "5.14.16-1" && echo PATCHED || echo STILL-VULNERABLE
RHEL 8 · kernel-rt · FIXED · kernel-rt-4.18.0-348.2.1.rt7.132.el8_5
sudo dnf upgrade --advisory=RHSA-2021:4646
rpm -q kernel-rt
RHEL 8 · kernel · FIXED · kernel-4.18.0-348.2.1.el8_5
sudo dnf upgrade --advisory=RHSA-2021:4647
rpm -q kernel
RHEL 8.4 Extended Update Support · kernel-rt · FIXED · kernel-rt-4.18.0-305.28.1.rt7.100.el8_4
sudo dnf upgrade --advisory=RHSA-2021:4648
rpm -q kernel-rt
RHEL 8.4 Extended Update Support · kernel · FIXED · kernel-4.18.0-305.28.1.el8_4
sudo dnf upgrade --advisory=RHSA-2021:4650
rpm -q kernel
RHEL 6 · kernel · NOT AFFECTED
Public exploits and detection
Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.
- GitHub PoC: zzhacked/CVE-2021-43267 (4 stars)
- GitHub PoC: DarkSprings/CVE-2021-43267-POC (0 stars)
- Write-up: cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.14.16
- GitHub PoC: ohnonoyesyes/CVE-2021-43267
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2021-43267?
linux kernel: upgrade to 5.10.77, 5.14.16; fedora: mitigate or apply the listed mitigation; h300s firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2021-43267 being exploited?
CVE-2021-43267 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2021-43267 affect?
CVE-2021-43267 affects linux kernel, fedora, h300s firmware. Severity is critical (CVSS 9.8). An issue was discovered in net/tipc/crypto.c in the Linux kernel before 5.14.16. The Transparent Inter-Process Communication (TIPC) functionality allows remote attackers to exploit insufficient validation of user-supplied sizes for the MSG_
How urgent is CVE-2021-43267?
Priority 74/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist
Software pages
Related CVEs
- CVE-2026-63912 CRITICAL 9.8 UPGRADE In the Linux kernel, the following vulnerability has been resolved: xfrm: esp: restore combined single-frag l
- CVE-2026-63913 HIGH 8.2 UPGRADE In the Linux kernel, the following vulnerability has been resolved: netfilter: conntrack: tcp: do not force C
- CVE-2026-63914 HIGH 7.3 UPGRADE In the Linux kernel, the following vulnerability has been resolved: xfrm: route MIGRATE notifications to call
- CVE-2026-63915 HIGH 8.8 UPGRADE In the Linux kernel, the following vulnerability has been resolved: nfc: hci: fix out-of-bounds read in HCP h
- CVE-2026-63916 HIGH 8.8 UPGRADE In the Linux kernel, the following vulnerability has been resolved: HID: wacom: Fix OOB write in wacom_hid_se