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NVD / CVE Program· CNA Linux

CVE-2026-43455: mctp: route: hold key->lock in mctp_flow_prepare_output()

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.11% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 0695712f3a6f1a48915f95767cfb42077683dcdc, 47893166bc5611ee9a20de6b8d2933b2320fb772, 7d86aa41c073c4e7eb75fd2e674f1fd8f289728a.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 0695712f3a6f1a48915f95767cfb42077683dcdc, 47893166bc5611ee9a20de6b8d2933b2320fb772, 7d86aa41c073c4e7eb75fd2e674f1fd8f289728a or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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_flow_prepare_output() via mctp_local_output() -> mctp_dst_output() without holding key->lock, so the check-and-set sequence is racy. Example interleaving: CPU0 CPU1 ---- ---- mctp_flow_prepare_output(key, devA) if (!key->dev) // sees NULL mctp_flow_prepare_output( key, devB) if (!key->dev) // still NULL mctp_dev_set_key(devB, key) mctp_dev_hold(devB) key->dev = devB mctp_dev_set_key(devA, key) mctp_dev_hold(devA) key->dev = devA // overwrites devB Now both devA and devB references were acquired, but only the final key->dev value is tracked for release. One reference can be lost, causing a resource leak as mctp_dev_release_key() would only decrease the reference on one dev. Fix by taking key->lock around the key->dev check and mctp_dev_set_key() call.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
May 8, 2026
Updated
Jun 17, 2026
EPSS
0.1% · 1th percentile
CWE
—

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.16 and later · before 6.1.167
  • linux linux kernel6.2 and later · before 6.6.130
  • linux linux kernel6.7 and later · before 6.12.78
  • linux linux kernel6.13 and later · before 6.18.19
  • linux linux kernel6.19 and later · before 6.19.9
  • linux linux kernel7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.16affected
    • 67737c457281dd199ceb9e31b6ba7efd3bfe566d and later · before 47893166bc5611ee9a20de6b8d2933b2320fb772affected · git
    • 67737c457281dd199ceb9e31b6ba7efd3bfe566d and later · before 86f5334fcb48a5b611c33364ab52ca684d0f6d91affected · git
    • 67737c457281dd199ceb9e31b6ba7efd3bfe566d and later · before 0695712f3a6f1a48915f95767cfb42077683dcdcaffected · git
    • 67737c457281dd199ceb9e31b6ba7efd3bfe566d and later · before 925a5ffd99cddd7a7e41d5ad120c7a2c6d50260faffected · git
    • 67737c457281dd199ceb9e31b6ba7efd3bfe566d and later · before 8d27d9b260dd19c1b519e1a13de6448f9984e30eaffected · git
    • 67737c457281dd199ceb9e31b6ba7efd3bfe566d and later · before 7d86aa41c073c4e7eb75fd2e674f1fd8f289728aaffected · git
    • before 5.16not affected · semver
    • 6.1.167 and later · up to and including 6.1.*not affected · semver
    • 6.6.130 and later · up to and including 6.6.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.170-16.1.170-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.19.10-16.19.10-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-43447May 8, 2026 · iavf: fix PTP use-after-free during reset
    31Monitor
  • ← EarlierCVE-2026-43454May 8, 2026 · netfilter: nf_tables: Fix for duplicate device in netdev hooks
    31Monitor
  • Later →CVE-2026-43457May 8, 2026 · mctp: i2c: fix skb memory leak in receive path
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0695712f3a6f1a48915f95767cfb42077683dcdcVendor (CNA)
Linux Linux47893166bc5611ee9a20de6b8d2933b2320fb772Vendor (CNA)
Linux Linux7d86aa41c073c4e7eb75fd2e674f1fd8f289728aVendor (CNA)
Linux Linux86f5334fcb48a5b611c33364ab52ca684d0f6d91Vendor (CNA)
Linux Linux8d27d9b260dd19c1b519e1a13de6448f9984e30eVendor (CNA)
Linux Linux925a5ffd99cddd7a7e41d5ad120c7a2c6d50260fVendor (CNA)
debian:linux6.1.170-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records