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TI-2026-50596 Aliases CVE-2026-72317GHSA-x2ff-m8pm-h936

SUNRPC: pin upper rpc_clnt across the TLS connect_worker

Priority MEDIUM 50Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 12 fixed, 1 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00644 51st percentileScored 2026-11-07
Fix Partial Linux (Linux): 6.6.145, 6.12.97, 6.18.40 +2Red Hat: 2 advisoriesRed Hat: 12 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux6.5 and later6.6.145, 6.12.97, 6.18.40, 7.1.5, 7.2Patch availableCNA
  • Linux VendorLinux Affected 6.5 and later Fixed in 6.6.145, 6.12.97, 6.18.40, 7.1.5, 7.2 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*——Linux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions — — ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 6.6.145, 6.12.97, 6.18.40, 7.1.5, 7.2

Red Hat 2 advisories

  • RHSA-2026:77689 Released 2026-10-08 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream (v. 9) kernel-64k-debug-devel-5.14.0-687.56.1.el9_8, kernel-64k-debug-devel-matched-5.14.0-687.56.1.el9_8, kernel-64k-devel-5.14.0-687.56.1.el9_8 +12
    • 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-64k-core-5.14.0-687.56.1.el9_8 +28
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) kernel-tools-libs-devel-5.14.0-687.56.1.el9_8, libperf-5.14.0-687.56.1.el9_8
    • 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-64k-core-5.14.0-687.56.1.el9_8 +21
    • 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-debug-5.14.0-687.56.1.el9_8 +9
  • RHSA-2026:77690 Released 2026-10-08 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • 10Base-SMTV kernel-modules-internal-6.12.0-211.64.1.el10_2
    • Red Hat Enterprise Linux AppStream (v. 10) kernel-64k-debug-devel-6.12.0-211.64.1.el10_2, kernel-64k-debug-devel-matched-6.12.0-211.64.1.el10_2, kernel-64k-devel-6.12.0-211.64.1.el10_2 +12
    • Red Hat Enterprise Linux BaseOS (v. 10) kernel-6.12.0-211.64.1.el10_2, kernel-64k-6.12.0-211.64.1.el10_2, kernel-64k-core-6.12.0-211.64.1.el10_2 +29
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) kernel-tools-libs-devel-6.12.0-211.64.1.el10_2, libperf-6.12.0-211.64.1.el10_2
    • Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal-6.12.0-211.64.1.el10_2
    • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt-6.12.0-211.64.1.el10_2, kernel-rt-64k-6.12.0-211.64.1.el10_2, kernel-rt-64k-core-6.12.0-211.64.1.el10_2 +21
    • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt-6.12.0-211.64.1.el10_2, kernel-rt-core-6.12.0-211.64.1.el10_2, kernel-rt-debug-6.12.0-211.64.1.el10_2 +9

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
10Base-SMTVFixed RHSA-2026:77690
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:77690
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2026:77689
Red Hat Enterprise Linux BaseOS (v. 10)Fixed RHSA-2026:77690
Red Hat Enterprise Linux BaseOS (v. 9)Fixed RHSA-2026:77689
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:77690
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)Fixed RHSA-2026:77689
Red Hat Enterprise Linux Hidden (v. 10)Fixed RHSA-2026:77690
Red Hat Enterprise Linux Real Time (v. 10)Fixed RHSA-2026:77690
Red Hat Enterprise Linux Real Time (v. 9)Fixed RHSA-2026:77689
Red Hat Enterprise Linux Real Time for NFV (v. 10)Fixed RHSA-2026:77690
Red Hat Enterprise Linux Real Time for NFV (v. 9)Fixed RHSA-2026:77689
Not affected: 3 products
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-72317
  2. 2026-10-03 Alias added: GHSA-x2ff-m8pm-h936
  3. 2026-10-09 Fix available: RHSA-2026:77689 · Red Hat
  4. 2026-10-09 Fix available: RHSA-2026:77690 · Red Hat
  5. 2026-10-09 Fix available: 10Base-SMTV, Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux AppStream (v. 9) +9 · Red Hat
  6. 2026-10-16 CISA SSVC decision points changed
  7. 2026-10-21 EPSS moved to the 50th–90th percentile
  8. 2026-10-26 CVSS score changed · Red Hat
  9. 2026-10-30 Affected versions changed · Red Hat

References

Other 5

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
See all 21727 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences