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NVD / CVE Program· CNA Linux

CVE-2026-74692: net/smc: fix TOCTOU race between smc_listen_out() and listener close

Noroxi assessment

Priority: Monitor (action score 30/100)

  • 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: 0.49% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 00f89433777236ced4771211047fb5d4cd581cea, 01865e1ddb126b25ac9eba5cdd7ec49e11183a64, 185a4caeecabc150106deda1da170b09f2ad803f; azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 6.6.152.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 00f89433777236ced4771211047fb5d4cd581cea, 01865e1ddb126b25ac9eba5cdd7ec49e11183a64, 185a4caeecabc150106deda1da170b09f2ad803f; azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 6.6.152.1-1 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: net/smc: fix TOCTOU race between smc_listen_out() and listener close smc_listen_out() reads lsmc->sk.sk_state without the listener lock, then acquires lock_sock_nested() only after the check passes. This opens a window where smc_close_active() can transition the listener to SMC_CLOSED, call smc_close_cleanup_listen() to drain the accept queue, and release the lock, all between the lockless read and the delayed lock acquisition: smc_listen_work (smc_hs_wq) smc_close_active() ------------------------------- ------------------------- release_sock(child) if (sk_state == SMC_LISTEN) TRUE lock_sock(listener) sk_state = SMC_CLOSED smc_close_cleanup_listen() release_sock(listener) flush_work(tcp_listen_work) lock_sock_nested(listener) smc_accept_enqueue(listener, child) /* child enqueued on dead listener */ smc_close_active() flushes only tcp_listen_work. Work items already dispatched onto smc_hs_wq for the CLC handshake continue running unguarded. smc_accept_enqueue() takes a sock_hold() on the child that is never released, so the child smc_sock, its clcsock, and the reference all leak. A remote peer that opens TCP connections while the server calls close() can exhaust kernel memory. Move lock_sock_nested() to before the sk_state check so that the test and the enqueue are atomic under the listener lock.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Aug 22, 2026
Updated
Oct 16, 2026
EPSS
0.4% · 41th percentile
CWE
—

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.5
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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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.

—

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

    • d1d004585b40c212b338fc8a40cbaaf230ea4703, 5.1affected
    • fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and later · before 53c7938d8bcfde3296ec1a347ba2a9393c1fdcfaaffected · git
    • fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and later · before feb71634bb1abab3e8fb5cde874b27001cc1282eaffected · git
    • fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and later · before 01865e1ddb126b25ac9eba5cdd7ec49e11183a64affected · git
    • fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and later · before 00f89433777236ced4771211047fb5d4cd581ceaaffected · git
    • fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and later · before 78e5ebcd1c10ed7c8bda0a99e0abd5b62da86d67affected · git
    • fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and later · before ff5bcd804b5bc5c64736b7d318c20e12ea9506b8affected · git
    • fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and later · before 185a4caeecabc150106deda1da170b09f2ad803faffected · git
    • 4.19.299 and later · before 4.20affected · semver
    • before 5.1not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.187-16.1.187-1
Debian:12linux-6.12before 6.12.107-1~deb12u16.12.107-1~deb12u1
Debian:13linuxbefore 6.12.105-16.12.105-1
Debian:14linuxbefore 7.1.9-17.1.9-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-74690Aug 22, 2026 · s390/ism: Fix UAF of sba and ieq during ism_dev_exit()
    33Monitor
  • ← EarlierCVE-2026-74691Aug 22, 2026 · net: thunderbolt: Tear down DMA paths before stopping the rings
    35Monitor
  • Later →CVE-2026-74693Aug 22, 2026 · net: prestera: validate firmware header length
    0Monitor

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 Linux00f89433777236ced4771211047fb5d4cd581ceaVendor (CNA)
Linux Linux01865e1ddb126b25ac9eba5cdd7ec49e11183a64Vendor (CNA)
Linux Linux185a4caeecabc150106deda1da170b09f2ad803fVendor (CNA)
Linux Linux4.20Vendor (CNA)
Linux Linux53c7938d8bcfde3296ec1a347ba2a9393c1fdcfaVendor (CNA)
Linux Linux78e5ebcd1c10ed7c8bda0a99e0abd5b62da86d67Vendor (CNA)
Linux Linuxfeb71634bb1abab3e8fb5cde874b27001cc1282eVendor (CNA)
Linux Linuxff5bcd804b5bc5c64736b7d318c20e12ea9506b8Vendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.06.6.152.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.187-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.107-1~deb12u1 · 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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • 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
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

nvd-secondary

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. SSVC exploitation— → none
  2. Fix✗ → ✓

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

References

Show all references (6 more)

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

All records