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NVD / CVE Program· CNA Linux

CVE-2026-31535: smb: client: make use of smbdirect_socket.recv_io.credits.available

MediumCVSS 4.7 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 18/100)

  • 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: 0.08% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: Linux Linux 9911b1ed187a770a43950bf51f340ad4b7beecba, be8845ad5d6558703d20567d8702155598325db8, f664e6e8a81103cb45c8802a9bc7499e0902c458.

Low priority for now. Upgrade to Linux Linux 9911b1ed187a770a43950bf51f340ad4b7beecba, be8845ad5d6558703d20567d8702155598325db8, f664e6e8a81103cb45c8802a9bc7499e0902c458 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: smb: client: make use of smbdirect_socket.recv_io.credits.available The logic off managing recv credits by counting posted recv_io and granted credits is racy. That's because the peer might already consumed a credit, but between receiving the incoming recv at the hardware and processing the completion in the 'recv_done' functions we likely have a window where we grant credits, which don't really exist. So we better have a decicated counter for the available credits, which will be incremented when we posted new recv buffers and drained when we grant the credits to the peer.

Published
Apr 24, 2026
Updated
Nov 11, 2026
EPSS
0.0% · 0th percentile

Report tools

JSON

Action score

18

Monitor

Low priority for now.

CVSS
18 / 40 · 4.7 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.0%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

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

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • 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.

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 kernel6.18 and later · before 6.18.11
  • linux linux kernel6.19 and later · before 6.19.1

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

    • 6.18affected
    • 5fb9b459b3686e366640edd4e62805ef7b4de927 and later · before f664e6e8a81103cb45c8802a9bc7499e0902c458affected · git
    • 5fb9b459b3686e366640edd4e62805ef7b4de927 and later · before be8845ad5d6558703d20567d8702155598325db8affected · git
    • 5fb9b459b3686e366640edd4e62805ef7b4de927 and later · before 9911b1ed187a770a43950bf51f340ad4b7beecbaaffected · git
    • before 6.18not affected · semver
    • 6.18.11 and later · up to and including 6.18.*not affected · semver
    • 6.19.1 and later · up to and including 6.19.*not affected · semver
    • 7.0 and laternot affected · original_commit_for_fix

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:14linuxbefore 6.18.12-16.18.12-1

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-2026-31532Apr 23, 2026 · can: raw: fix ro->uniq use-after-free in raw_rcv()
    31Monitor
  • ← EarlierCVE-2026-31533Apr 23, 2026 · net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption
    39Monitor
  • Later →CVE-2026-31536Apr 24, 2026 · smb: server: let send_done handle a completion without IB_SEND_SIGNALED
    39Monitor

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 Linux9911b1ed187a770a43950bf51f340ad4b7beecbaVendor (CNA)
Linux Linuxbe8845ad5d6558703d20567d8702155598325db8Vendor (CNA)
Linux Linuxf664e6e8a81103cb45c8802a9bc7499e0902c458Vendor (CNA)
debian:linux6.18.12-1 · Debian:14Package 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.

  • CVE-2025-38352276 days apartposix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()KEV
    61This week
  • CVE-2026-6409186 days apartbatman-adv: tt: fix TOCTOU race for reported vlans
    39Monitor
  • CVE-2026-6403486 days apartnet: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer
    37Monitor
  • CVE-2026-6393786 days apartKVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer
    35Monitor
  • CVE-2026-6386786 days apartmptcp: close TOCTOU race while computing rcv_wnd
    32Monitor
  • CVE-2026-316781 days apartopenvswitch: defer tunnel netdev_put to RCU release
    31Monitor

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).

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.
  • Special conditions such as timing or configuration are required.

If successful

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

Weakness class (CWE)

CWE-367 · Time-of-check Time-of-use (TOCTOU) Race Condition

CVSS vector

CVSS:3.1/AV:L/AC:H/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.

ATT&CK techniques

—

Change log

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

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

References

Show all references (2 more)

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

All records