CVE-2026-43455: In the Linux kernel, the following vulnerability has been resolved: mctp: route: hold key->lock in mctp_flow_

Q: How do I fix CVE-2026-43455?

linux kernel: upgrade to 6.1.167, 6.6.130, 6.12.78, 6.18.19, 6.19.9. Exact commands for each OS are on this page.

Q: Is CVE-2026-43455 being exploited?

CVE-2026-43455 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-43455 affect?

CVE-2026-43455 affects linux kernel. Severity is medium (CVSS 5.5). In the Linux kernel, the following vulnerability has been resolved: mctp: route: hold key->lock in mctp_flow_prepare_output() mctp_flow_prepare_output() checks key->dev and may call mctp_dev_set_key(), but it does not hold key->lock while

Routine

MEDIUM 5.5WATCHLISTUPGRADE

CVE-2026-43455 is a medium-severity flaw (CVSS 5.5) affecting linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In the Linux kernel, the following vulnerability has been resolved: mctp: route: hold key->lock in mctp_flow_prepare_output() mctp_flow_prepare_output() checks key->dev and may call mctp_dev_set_key(), but it does not hold key->lock while doing so. mctp_dev_set_key() and mctp_dev_release_key() are annotated with __must_hold(&key->lock), so key->dev access is intended to be serialized by key->lock. The mctp_sendmsg() transmit path reaches mctp_

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.1% (top 99%)
CISA exploited list	No
Published	2026-05-08
Last modified	2026-06-17

Publisher (CNA): kernel.org · Vendor: linux

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-08 15:16 UTCPublished CVE record published
2026-06-17 10:49 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 5.16 and < 6.1.167 · >= 6.2 and < 6.6.130 · >= 6.7 and < 6.12.78 · >= 6.13 and < 6.18.19 · >= 6.19 and < 6.19.9 · 7.0 rc1 · 7.0 rc2 · 7.0 rc3

Fixed in: 6.1.167, 6.6.130, 6.12.78, 6.18.19, 6.19.9

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.

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.

Quick answers

How do I fix CVE-2026-43455?

linux kernel: upgrade to 6.1.167, 6.6.130, 6.12.78, 6.18.19, 6.19.9. Exact commands for each OS are on this page.

Is CVE-2026-43455 being exploited?

CVE-2026-43455 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-2026-43455 affect?

CVE-2026-43455 affects linux kernel. Severity is medium (CVSS 5.5). In the Linux kernel, the following vulnerability has been resolved: mctp: route: hold key->lock in mctp_flow_prepare_output() mctp_flow_prepare_output() checks key->dev and may call mctp_dev_set_key(), but it does not hold key->lock while

How urgent is CVE-2026-43455?

Priority 25/100. On your watchlist

Software pages

Linux kernel vulnerabilities

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References

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