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Fencer Vulns
high 7.5

CVE-2026-31539 json

smb: smbdirect: introduce smbdirect_socket.recv_io.credits.available

published 2026-04-24 6 mo ago modified 2026-10-19 20 d ago also EUVD-2026-25432

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 26%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

smb: smbdirect: introduce 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.

Patch / fix

  • Linux Linux 6.18.11, 6.19.1, 7.0
  • linux Debian 14 6.18.12-1

debian advisories DEBIAN-CVE-2026-31539

  • kernel RHEL 9 5.14.0-687.52.1.el9_8
  • rv RHEL 9 5.14.0-687.52.1.el9_8
  • perf RHEL 9 5.14.0-687.52.1.el9_8
  • rtla RHEL 9 5.14.0-687.52.1.el9_8
  • libperf RHEL 9 5.14.0-687.52.1.el9_8
  • kernel-rt RHEL 9 5.14.0-687.52.1.el9_8
  • kernel-64k RHEL 9 5.14.0-687.52.1.el9_8
  • kernel-core RHEL 9 5.14.0-687.52.1.el9_8

red hat advisories RHSA-2026:71700RHSA-2026:67471

  • kernel AlmaLinux 9 5.14.0-687.52.1.el9_8
  • rv AlmaLinux 9 5.14.0-687.52.1.el9_8
  • perf AlmaLinux 9 5.14.0-687.52.1.el9_8
  • rtla AlmaLinux 9 5.14.0-687.52.1.el9_8
  • libperf AlmaLinux 9 5.14.0-687.52.1.el9_8
  • kernel-rt AlmaLinux 9 5.14.0-687.52.1.el9_8
  • kernel-64k AlmaLinux 9 5.14.0-687.52.1.el9_8
  • kernel-core AlmaLinux 9 5.14.0-687.52.1.el9_8

almalinux advisories ALSA-2026:71700ALSA-2026:67471

  • kernel Rocky Linux 9 5.14.0-687.52.1.el9_8
  • kernel Rocky Linux 10 6.12.0-211.55.1.el10_2

rocky linux advisories RLSA-2026:71700RLSA-2026:67471

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-31539 updated cvss 7.0

kernel: smb: smbdirect: introduce smbdirect_socket.recv_io.credits.available

  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.52.1.el9_8, perf 5.14.0-687.52.1.el9_8, rtla 5.14.0-687.52.1.el9_8, python3-perf 5.14.0-687.52.1.el9_8, kernel-devel-matched 5.14.0-687.52.1.el9_8, kernel-64k-devel-matched 5.14.0-687.52.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:71700
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.55.1.el10_2, perf 6.12.0-211.55.1.el10_2, rtla 6.12.0-211.55.1.el10_2, python3-perf 6.12.0-211.55.1.el10_2, kernel-devel-matched 6.12.0-211.55.1.el10_2, kernel-64k-devel-matched 6.12.0-211.55.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:67471
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.52.1.el9_8, kernel-64k 5.14.0-687.52.1.el9_8, kernel-core 5.14.0-687.52.1.el9_8, kernel-tools 5.14.0-687.52.1.el9_8, kernel-modules 5.14.0-687.52.1.el9_8, kernel-64k-core 5.14.0-687.52.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:71700
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.55.1.el10_2, kernel-64k 6.12.0-211.55.1.el10_2, kernel-core 6.12.0-211.55.1.el10_2, kernel-tools 6.12.0-211.55.1.el10_2, kernel-modules 6.12.0-211.55.1.el10_2, kernel-64k-core 6.12.0-211.55.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:67471
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.52.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.52.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.52.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.52.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.52.1.el9_8
    fixed: vendor fix RHSA-2026:71700
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.55.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.55.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.55.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.55.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.55.1.el10_2
    fixed: vendor fix RHSA-2026:67471
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.52.1.el9_8, kernel-rt-64k 5.14.0-687.52.1.el9_8, kernel-rt-core 5.14.0-687.52.1.el9_8, kernel-rt-modules 5.14.0-687.52.1.el9_8, kernel-rt-64k-core 5.14.0-687.52.1.el9_8, kernel-rt-debug-core 5.14.0-687.52.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:71700
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.55.1.el10_2, kernel-rt-64k 6.12.0-211.55.1.el10_2, kernel-rt-core 6.12.0-211.55.1.el10_2, kernel-rt-modules 6.12.0-211.55.1.el10_2, kernel-rt-64k-core 6.12.0-211.55.1.el10_2, kernel-rt-debug-core 6.12.0-211.55.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:67471
show 3 more
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.52.1.el9_8, kernel-rt-core 5.14.0-687.52.1.el9_8, kernel-rt-modules 5.14.0-687.52.1.el9_8, kernel-rt-debug-core 5.14.0-687.52.1.el9_8, kernel-rt-modules-core 5.14.0-687.52.1.el9_8, kernel-rt-debug-modules 5.14.0-687.52.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:71700
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.55.1.el10_2, kernel-rt-core 6.12.0-211.55.1.el10_2, kernel-rt-modules 6.12.0-211.55.1.el10_2, kernel-rt-debug-core 6.12.0-211.55.1.el10_2, kernel-rt-modules-core 6.12.0-211.55.1.el10_2, kernel-rt-debug-modules 6.12.0-211.55.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:67471
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
24 d ago

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.