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Fencer Intel
critical 9.8

CVE-2026-72317 in the critical feed json

SUNRPC: pin upper rpc_clnt across the TLS connect_worker

published 2mo ago modified 26d ago also EUVD-2026-59216

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 51%
public exploits
0
none known

Summary

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

SUNRPC: pin upper rpc_clnt across the TLS connect_worker

The TLS connect path has a use-after-free: nothing pins the upper rpc_clnt across the delayed connect_worker. xs_connect() stores task->tk_client in sock_xprt::clnt as a raw pointer and queues the worker; for TLS-secured transports that worker is xs_tcp_tls_setup_socket(), which reads several fields out of the saved pointer (cl_timeout, cl_program, cl_prog, cl_vers, cl_cred, cl_stats) to construct the args for the inner handshake rpc_clnt.

The xprt does not reference the rpc_clnt; the rpc_clnt references the xprt. xs_destroy() does cancel the connect_worker, but it runs only when the xprt's refcount drops to zero, which cannot happen until the rpc_clnt releases its cl_xprt reference in rpc_free_client_work(). When a TLS handshake fails fatally (for example, an mTLS mount whose client cert does not match the server), the connecting task is woken with -EACCES and exits, the mount caller invokes rpc_shutdown_client(), and the upper rpc_clnt is freed before the queued connect_worker fires. xs_tcp_tls_setup_socket() then dereferences the freed clnt, producing the refcount_t underflow Michael Nemanov reported.

Take a reference on the upper rpc_clnt in xs_connect() for TLS transports via a new rpc_hold_client() helper, and drop it in the connect_worker's exit path with rpc_release_client(). The xprt_lock_connect() / xprt_unlock_connect() pairing already serialises xs_connect() with xs_tcp_tls_setup_socket(), so the take and release are balanced one-for-one.

The non-TLS connect worker (xs_tcp_setup_socket) never reads sock_xprt::clnt, so leave that path alone and avoid the clnt-holds-xprt-holds-clnt cycle that would otherwise prevent xprt destruction.

Patch / fix

  • Linux Linux 6.6.145, 6.12.97, 6.18.40, 7.1.5, 7.2
  • linux Debian 13 6.12.100-1
  • linux Debian 14 7.1.5-1

debian advisories DEBIAN-CVE-2026-72317

  • linux Ubuntu 24.04 LTS 6.8.0-147.147
  • linux Ubuntu 26.04 LTS 7.0.0-34.34
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1067.70
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1013.13
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1071.79
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1013.13
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1066.74
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1007.8

ubuntu advisories UBUNTU-CVE-2026-72317

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 10.2 6.12.0-211.64.1.el10_2
  • rv RHEL 10.2 6.12.0-211.64.1.el10_2
  • perf RHEL 10.2 6.12.0-211.64.1.el10_2
  • rtla RHEL 10.2 6.12.0-211.64.1.el10_2
  • libperf RHEL 10.2 6.12.0-211.64.1.el10_2
  • kernel-rt RHEL 10.2 6.12.0-211.64.1.el10_2
  • kernel-64k RHEL 10.2 6.12.0-211.64.1.el10_2
  • kernel-core RHEL 10.2 6.12.0-211.64.1.el10_2

red hat advisories RHSA-2026:77690RHSA-2026:77689

  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.81.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.81.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.81.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-obs-build SLE Module for Development Tools 15 SP7 6.4.0-150700.53.81.1
  • kernel-default-base SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1.150700.17.45.1

suse advisories SUSE-SU-2026:4254-1SUSE-SU-2026:4369-1SUSE-SU-2026:23887-1SUSE-SU-2026:23902-1SUSE-SU-2026:23897-1SUSE-SU-2026:23881-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.38.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.38.1

opensuse advisories openSUSE-SU-2026:21910-1

  • kernel AlmaLinux 9 5.14.0-687.56.1.el9_8
  • rv AlmaLinux 9 5.14.0-687.56.1.el9_8
  • perf AlmaLinux 9 5.14.0-687.56.1.el9_8
  • rtla AlmaLinux 9 5.14.0-687.56.1.el9_8
  • libperf AlmaLinux 9 5.14.0-687.56.1.el9_8
  • kernel-rt AlmaLinux 9 5.14.0-687.56.1.el9_8
  • kernel-64k AlmaLinux 9 5.14.0-687.56.1.el9_8
  • kernel-core AlmaLinux 9 5.14.0-687.56.1.el9_8

almalinux advisories ALSA-2026:77689ALSA-2026:77690

  • kernel Rocky Linux 10 6.12.0-211.64.1.el10_2
  • kernel Rocky Linux 9 5.14.0-687.56.1.el9_8

rocky linux advisories RLSA-2026:77690RLSA-2026:77689

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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-2026-72317 updated cvss 6.5

kernel: SUNRPC: pin upper rpc_clnt across the TLS connect_worker

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux kernel-modules-internal 6.12.0-211.64.1.el10_2
    fixed: vendor fix RHSA-2026:77690
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.56.1.el9_8, perf 5.14.0-687.56.1.el9_8, rtla 5.14.0-687.56.1.el9_8, python3-perf 5.14.0-687.56.1.el9_8, kernel-devel-matched 5.14.0-687.56.1.el9_8, kernel-64k-devel-matched 5.14.0-687.56.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:77689
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.64.1.el10_2, rv 6.12.0-264.14.1.el10_3, perf 6.12.0-211.64.1.el10_2, perf 6.12.0-264.14.1.el10_3, rtla 6.12.0-211.64.1.el10_2, rtla 6.12.0-264.14.1.el10_3, +20 more
    fixed: vendor fix RHSA-2026:77690
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.56.1.el9_8, kernel-64k 5.14.0-687.56.1.el9_8, kernel-core 5.14.0-687.56.1.el9_8, kernel-tools 5.14.0-687.56.1.el9_8, kernel-modules 5.14.0-687.56.1.el9_8, kernel-64k-core 5.14.0-687.56.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:77689
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.64.1.el10_2, kernel 6.12.0-264.14.1.el10_3, kernel-64k 6.12.0-211.64.1.el10_2, kernel-64k 6.12.0-264.14.1.el10_3, kernel-core 6.12.0-211.64.1.el10_2, kernel-core 6.12.0-264.14.1.el10_3, +62 more
    fixed: vendor fix RHSA-2026:77690
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.56.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.56.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.56.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.56.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.56.1.el9_8
    fixed: vendor fix RHSA-2026:77689
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.64.1.el10_2, libperf 6.12.0-264.14.1.el10_3, kernel-debuginfo-common-s390x 6.12.0-211.64.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-264.14.1.el10_3, kernel-debuginfo-common-x86_64 6.12.0-211.64.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-264.14.1.el10_3, +4 more Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal 6.12.0-211.64.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.64.1.el10_2
    fixed: vendor fix RHSA-2026:77690
show 5 more
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.56.1.el9_8, kernel-rt-64k 5.14.0-687.56.1.el9_8, kernel-rt-core 5.14.0-687.56.1.el9_8, kernel-rt-modules 5.14.0-687.56.1.el9_8, kernel-rt-64k-core 5.14.0-687.56.1.el9_8, kernel-rt-debug-core 5.14.0-687.56.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:77689
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.64.1.el10_2, kernel-rt 6.12.0-264.14.1.el10_3, kernel-rt-64k 6.12.0-211.64.1.el10_2, kernel-rt-64k 6.12.0-264.14.1.el10_3, kernel-rt-core 6.12.0-211.64.1.el10_2, kernel-rt-core 6.12.0-264.14.1.el10_3, +34 more
    fixed: vendor fix RHSA-2026:77690
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.56.1.el9_8, kernel-rt-core 5.14.0-687.56.1.el9_8, kernel-rt-modules 5.14.0-687.56.1.el9_8, kernel-rt-debug-core 5.14.0-687.56.1.el9_8, kernel-rt-modules-core 5.14.0-687.56.1.el9_8, kernel-rt-debug-modules 5.14.0-687.56.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:77689
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.64.1.el10_2, kernel-rt 6.12.0-264.14.1.el10_3, kernel-rt-core 6.12.0-211.64.1.el10_2, kernel-rt-core 6.12.0-264.14.1.el10_3, kernel-rt-modules 6.12.0-211.64.1.el10_2, kernel-rt-modules 6.12.0-264.14.1.el10_3, +15 more
    fixed: vendor fix RHSA-2026:77690
  • 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
total
Assessed
26d ago

Exploit prediction

0.64% chance of exploitation in the next 30 days, higher than 51% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Intel 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.