Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Linux | Linux | 6.5 | 6.6.145 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 7.1.5-1 | — |
| Debian 13 | linux | 6.12.100-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Nvidia-BlueField 24.04 LTS | linux-bluefield | 6.8.0-1033.38 | — |
| Ubuntu 26.04 LTS | linux | 7.0.0-34.34 | USN-8816-1 |
| Ubuntu 26.04 LTS | linux-aws +1 | 7.0.0-1013.13 | USN-8816-2, USN-8816-1 |
| Ubuntu 26.04 LTS | linux-azure | 7.0.0-1017.17 | USN-8888-1 |
| Ubuntu 26.04 LTS | linux-azure-fde | 7.0.0-1016.16 | USN-8888-1 |
| Ubuntu 26.04 LTS | linux-gke | 7.0.0-1007.8 | USN-8816-4 |
| Ubuntu 26.04 LTS | linux-ibm +1 | 7.0.0-1014.14 | USN-8816-2, USN-8816-1 |
| Ubuntu 26.04 LTS | linux-nvidia | 7.0.0-1025.26 | USN-9043-1 |
| Ubuntu 26.04 LTS | linux-nvidia-bos | 7.0.0-2022.23 | USN-9003-1 |
| Ubuntu 26.04 LTS | linux-oracle | 7.0.0-1012.12 | USN-8816-1 |
| Ubuntu 26.04 LTS | linux-raspi | 7.0.0-1020.20 | USN-8816-1 |
| Ubuntu 26.04 LTS | linux-riscv +1 | 7.0.0-34.34.1 | USN-8816-1 |
| Ubuntu 24.04 LTS | linux | 6.8.0-147.147 | USN-8917-1 |
| Ubuntu 24.04 LTS | linux-aws +1 | 6.8.0-1067.70 | USN-9024-1, USN-8917-1 |
| Ubuntu 24.04 LTS | linux-aws-7.0 +1 | 7.0.0-1013.13~24.04.1 | USN-8816-2, USN-8816-1 |
| Ubuntu 24.04 LTS | linux-azure-7.0 | 7.0.0-1017.17~24.04.1 | USN-8888-2 |
| Ubuntu 24.04 LTS | linux-azure-fde | 6.8.0-1069.76 | USN-8918-1 |
| Ubuntu 24.04 LTS | linux-azure-fde-7.0 | 7.0.0-1016.16~24.04.1 | USN-8888-2 |
| Ubuntu 24.04 LTS | linux-gcp +1 | 6.8.0-1071.79 | USN-8918-1, USN-8917-1 |
| Ubuntu 24.04 LTS | linux-gke | 6.8.0-1066.74 | USN-8917-1 |
| Ubuntu 24.04 LTS | linux-gkeop | 6.8.0-1052.56 | USN-8917-1 |
| Ubuntu 24.04 LTS | linux-hwe-7.0 | 7.0.0-34.34~24.04.1 | USN-8816-1 |
| Ubuntu 24.04 LTS | linux-ibm | 6.8.0-1067.68 | USN-8917-1 |
| Ubuntu 24.04 LTS | linux-lowlatency | 6.8.0-147.147.1 | USN-8917-1 |
| Ubuntu 24.04 LTS | linux-nvidia-7.0 | 7.0.0-1024.25~24.04.1 | USN-9003-1 |
| Ubuntu 24.04 LTS | linux-nvidia-lowlatency | 6.8.0-1067.70.1 | USN-9040-1 |
| Ubuntu 24.04 LTS | linux-nvidia-tegra | 6.8.0-1035.38 | USN-8781-1 |
| Ubuntu 24.04 LTS | linux-oracle | 6.8.0-1064.67 | USN-8917-1 |
| Ubuntu 24.04 LTS | linux-oracle-7.0 | 7.0.0-1012.12~24.04.1 | USN-8816-3 |
| Ubuntu 24.04 LTS | linux-raspi | 6.8.0-1068.72 | USN-9025-1 |
| Ubuntu 24.04 LTS | linux-riscv +29 | No fix yet | — |
| Ubuntu 24.04 LTS | linux-riscv-7.0 | 7.0.0-34.34.1~24.04.1 | — |
| Ubuntu 24.04 LTS | linux-vmware | 6.8.0-1008.8 | — |
| Ubuntu 22.04 LTS | linux-aws-6.8 | 6.8.0-1069.74~22.04.1 | USN-9024-1 |
| Ubuntu 22.04 LTS | linux-azure-6.8 | 6.8.0-1073.82~22.04.1 | USN-9026-1 |
| Ubuntu 22.04 LTS | linux-azure-fde-6.8 | 6.8.0-1071.78~22.04.1 | USN-9026-1 |
| Ubuntu 22.04 LTS | linux-gcp-6.8 | 6.8.0-1073.81~22.04.1 | USN-9024-1 |
| Ubuntu 22.04 LTS | linux-hwe-6.8 | 6.8.0-149.149~22.04.1 | USN-9066-1 |
| Ubuntu 22.04 LTS | linux-ibm-6.8 | 6.8.0-1069.70~22.04.1 | USN-9024-1 |
| Ubuntu 22.04 LTS | linux-lowlatency-hwe-6.8 | 6.8.0-149.149.1~22.04.1 | USN-9024-1 |
| Ubuntu 22.04 LTS | linux-oracle-6.8 | 6.8.0-1067.71~22.04.1 | USN-9025-1 |
| Ubuntu 22.04 LTS | linux-riscv +33 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-gke +28 | No fix yet | — |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | linux-gcp +14 | No fix yet | — |
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
| Ubuntu Pro Realtime 24.04 LTS | linux-raspi-realtime | 6.8.0-2056.58 | USN-9025-1 |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime | 6.8.1-1062.63 | USN-8917-1 |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime-6.14 +1 | No fix yet | — |
| Ubuntu Pro Realtime 22.04 LTS | linux-realtime-6.8 | 6.8.1-1064.65~22.04.1 | USN-9024-1 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-aws-fips | 6.8.0-1067.70+fips1 | USN-8917-1 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-fips | 6.8.0-147.147+fips1 | USN-8917-1 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-gcp-fips +1 | 6.8.0-1071.79+fips1 | USN-8918-1, USN-8917-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | rv +77 | 6.12.0-211.64.1.el10_2 | RHSA-2026:98608, RHSA-2026:77690 |
| RHEL 9 | rv +75 | 5.14.0-687.56.1.el9_8 | RHSA-2026:77689 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Shadow Migration Toolkit 10 | kernel-modules-internal | 6.12.0-211.64.1.el10_2 | RHSA-2026:77690 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | rv +74 | 6.12.0-211.64.1.el10_2 | ALSA-2026:77690 |
| AlmaLinux 9 | rv +73 | 5.14.0-687.56.1.el9_8 | ALSA-2026:77689 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | kernel | 6.12.0-211.64.1.el10_2 | RLSA-2026:77690 |
| Rocky Linux 9 | kernel | 5.14.0-687.56.1.el9_8 | RLSA-2026:77689 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | kernel-64kb +7 | 6.4.0-150700.53.81.1 | SUSE-SU-2026:4254-1 |
| SLES 15 SP7 | kernel-default-base | 6.4.0-150700.53.81.1.150700.17.45.1 | SUSE-SU-2026:4254-1 |
| SLES 15 SP6 | kernel-64kb +6 | 6.4.0-150600.23.135.1 | SUSE-SU-2026:4369-1 |
| SLES 15 SP6 | kernel-default-base | 6.4.0-150600.23.135.1.150600.12.62.4 | SUSE-SU-2026:4369-1 |
Show 9 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | kernel-64kb +8 | 6.12.0-160000.38.1 | SUSE-SU-2026:23902-1 |
| SLES for SAP 16.0 | kernel-default-base | 6.12.0-160000.38.1.160000.2.23 | SUSE-SU-2026:23902-1 |
| SLES for SAP 15 SP6 | kernel-default-base | 6.4.0-150600.23.135.1.150600.12.62.4 | SUSE-SU-2026:4369-1 |
| SLES for SAP 15 SP6 | kernel-docs +4 | 6.4.0-150600.23.135.1 | SUSE-SU-2026:4369-1 |
| SLES 16.0 | kernel-64kb +8 | 6.12.0-160000.38.1 | SUSE-SU-2026:23902-1, SUSE-SU-2026:23897-1 |
| SLES 16.0 | kernel-default-base | 6.12.0-160000.38.1.160000.2.23 | SUSE-SU-2026:23902-1 |
| SLE Micro 6.2 | kernel-default-base | 6.12.0-160000.38.1.160000.2.23 | SUSE-SU-2026:23887-1 |
| SLE Micro 6.2 | kernel-rt +5 | 6.12.0-160000.38.1 | SUSE-SU-2026:23887-1, SUSE-SU-2026:23881-1 |
| SLE Micro 6.1 | kernel-default-base | 6.4.0-52.1.21.34 | SUSE-SU-2026:23529-1 |
| SLE Micro 6.1 | kernel-rt +4 | 6.4.0-52.1 | SUSE-SU-2026:23529-1, SUSE-SU-2026:23528-1 |
| SLE Micro 6.0 | kernel-default-base | 6.4.0-52.1.21.36 | SUSE-SU-2026:23481-1 |
| SLE Micro 6.0 | kernel-rt +4 | 6.4.0-52.1 | SUSE-SU-2026:23481-1, SUSE-SU-2026:23477-1 |
| SLE Live Patching 15 SP7 | kernel-default | 6.4.0-150700.53.81.1 | SUSE-SU-2026:4254-1 |
| SLE Live Patching 15 SP7 | kernel-livepatch-SLE15-SP7-RT_Update_20 | 1-150700.1.3.1 | SUSE-SU-2026:4120-1 |
| SLE Live Patching 15 SP7 | kernel-livepatch-SLE15-SP7_Update_21 | 1-150700.15.3.1 | SUSE-SU-2026:4254-1 |
| SLE Live Patching 15 SP6 | kernel-default | 6.4.0-150600.23.135.1 | SUSE-SU-2026:4369-1 |
| SLE Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6_Update_31 | 1-150600.13.3.4 | SUSE-SU-2026:4369-1 |
| SUSE Real Time Module 15 SP7 | kernel-rt +2 | 6.4.0-150700.7.75.1 | SUSE-SU-2026:4120-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | kernel-default-base | 6.12.0-160000.38.1.160000.2.22 | openSUSE-SU-2026:21910-1 |
| openSUSE Leap 16.0 | kernel-rt +11 | 6.12.0-160000.38.1 | openSUSE-SU-2026:21910-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | kernel-livepatch-6.18.41-94.142 +1 | 1:1.0-0.amzn2023 | ALAS2023-2026-2071, ALAS2023-2026-2057 |
| Amazon Linux 2023 | perf6.12 +11 | 1:6.12.100-125.179.amzn2023 | ALAS2023-2026-2057 |
| Amazon Linux 2023 | perf6.18 +12 | 1:6.18.41-94.142.amzn2023 | ALAS2023-2026-2071 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | rv +29 | 6.12.0-211.64.1.el10_2 | ELSA-2026-77690 |
| Oracle Linux 9 | kernel-uek +34 | 6.12.0-206.104.3.3.el10uek | ELSA-2026-500248 |
| Oracle Linux 9 | rv +28 | 5.14.0-687.56.1.el9_8 | ELSA-2026-77689 |
Advisories 41
- USN-8917-1 linux, linux-aws, linux-aws-fips, linux-fips, linux-gcp, linux-gcp-fips, linux-gke, linux-gkeop, linux-ibm, linux-lowlatency, linux-oracle, linux-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-9025-1 linux-oracle-6.8, linux-raspi, linux-raspi-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-9024-1 linux-aws-6.8, linux-gcp-6.8, linux-ibm-6.8, linux-lowlatency-hwe-6.8, linux-nvidia, linux-realtime-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-9026-1 linux-azure-6.8, linux-azure-fde-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-9040-1 linux-nvidia-lowlatency vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-9066-1 linux-hwe-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8918-1 linux-azure, linux-azure-fde, linux-azure-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8888-2 linux-azure-7.0, linux-azure-fde-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-9003-1 linux-nvidia-7.0, linux-nvidia-bos vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-9043-1 linux-nvidia vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8888-1 linux-azure, linux-azure-fde vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- RHSA-2026:98608 Red Hat Security Advisory: kernel security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:77689 Red Hat Security Advisory: kernel security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:77690 Red Hat Security Advisory: kernel security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- WID-SEC-2026-2852 Linux Kernel: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 2026
- USN-8816-1 linux, linux-aws, linux-aws-7.0, linux-hwe-7.0, linux-ibm, linux-oracle, linux-raspi, linux-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8816-2 linux-gcp, linux-gcp-7.0, linux-oem-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8816-4 linux-gke vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8816-3 linux-oracle-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8781-1 linux-nvidia-tegra vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- ALSA-2026:77689 Important: kernel security, bug fix, and enhancement update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:77690 Important: kernel security, bug fix, and enhancement update AlmaLinux Security Advisories · Oct 29, 2026
- RLSA-2026:77689 Important: kernel security, bug fix, and enhancement update Rocky Linux Security Advisories · Oct 9, 2026
- RLSA-2026:77690 Important: kernel security, bug fix, and enhancement update Rocky Linux Security Advisories · Oct 9, 2026
- SUSE-SU-2026:4254-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Oct 8, 2026
- ELSA-2026-77690 Important: kernel security, bug fix, and enhancement update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Oct 8, 2026
- ELSA-2026-77689 Important: kernel security, bug fix, and enhancement update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Oct 8, 2026
- SUSE-SU-2026:4369-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Oct 2, 2026
- SUSE-SU-2026:23902-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 30, 2026
- SUSE-SU-2026:23881-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 30, 2026
- SUSE-SU-2026:23887-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 30, 2026
- SUSE-SU-2026:23897-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 30, 2026
- openSUSE-SU-2026:21910-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 25, 2026
- SUSE-SU-2026:23528-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 15, 2026
- SUSE-SU-2026:23529-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 15, 2026
- ALAS2023-2026-2071 Important: kernel6.18 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Sep 15, 2026
- SUSE-SU-2026:23477-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 14, 2026
- SUSE-SU-2026:4120-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 14, 2026
- SUSE-SU-2026:23481-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Sep 14, 2026
- ALAS2023-2026-2057 Important: kernel6.12 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Sep 9, 2026
- ELSA-2026-500248 Important: Unbreakable Enterprise kernel security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Sep 4, 2026
References
- https://git.kernel.org/stable/c/79cd550f8c884523b604fbfa43eb02def74d6224
- https://git.kernel.org/stable/c/7a65b41b657b71d5a77861f47dd13eb4bc8e10d0
- https://git.kernel.org/stable/c/5b0427ba582d143a364301f825f4e32272f06d2d
- https://git.kernel.org/stable/c/d49f6d098ed48775b9d27a9f9c5c220fdf76f102
- https://git.kernel.org/stable/c/46bc86c833956219bbfd246c1ffd832a479c5199