CVE-2023-53525
Medium · 5.5CVSS
5.5
EPSS
0.1%
Published
Oct 1, 2025
CISA due date
—
Cloudanix analysis
A Linux kernel bug could make computers using specialized fast-networking hardware crash when certain multicast features are used.
- Exploitation
- Local Privilege
- Attacker needs
- Low Privilege
- Complexity
- Low
- Impact
- Denial Of Service
- Component
- OS kernel
- Class
- Memory Corruption
- Remediation
- Upgrade
- Effort
- Medium
- Patch risk
- Low
What it actually does
The flaw permits a non-UD queue pair type to invoke RDMA multicast join, causing the ib->rec.qkey field to be read without initialization in cma_set_qkey and cma_make_mc_event, resulting in undefined kernel behavior or crash.
Why it matters to the business
RDMA-dependent workloads on affected Linux systems may encounter sudden kernel instability or panics during multicast operations, interrupting high-performance networking, storage, or compute clusters until kernels are updated.
How an attack unfolds
A local attacker invokes the ucma join_multicast path with an incompatible qp_type through the RDMA userspace interface, reaching the uninitialized qkey access inside the kernel's cma_iboe_join_multicast and cma_make_mc_event functions.
How to fix it
Update to a fixed kernel containing commit ae11498851423d6de27aebfe12a5ee85060ab1d5 or Debian packages 5.10.46-1 and later; restrict unprivileged access to RDMA interfaces until patched.
How to confirm the fix worked
Confirm running kernel contains the referenced commit or package version; exercise RDMA multicast join operations while monitoring for KMSAN or uninit-value warnings.
Typical attack path
- Obtain local user access on a system with RDMA hardware or emulation
- Open /dev/infiniband/rdma_cm and issue a join_multicast request via ucma
- Specify a qp_type other than UD or an uninitialized qkey
- Trigger the cma_iboe_join_multicast code path leading to uninit-value read
How to detect it
Search kernel logs and dmesg for KMSAN uninit-value reports mentioning cma_set_qkey, cma_make_mc_event, or rdma_join_multicast; inspect user processes performing writes to ucma device nodes.
What your security team should do
- Prioritize kernel upgrades on all systems exposing RDMA interfaces
- Limit RDMA device access to trusted processes via permissions or cgroups
- Add kernel crash and KMSAN log monitoring for cma_make_mc_event symbols
The record
In the Linux kernel, the following vulnerability has been resolved: RDMA/cma: Allow UD qp_type to join multicast only As for multicast: - The SIDR is the only mode that makes sense; - Besides PS_UDP, other port spaces like PS_IB is also allowed, as it is UD compatible. In this case qkey also needs to be set [1]. This patch allows only UD qp_type to join multicast, and set qkey to default if it's not set, to fix an uninit-value error: the ib->rec.qkey field is accessed without being initialized. ===================================================== BUG: KMSAN: uninit-value in cma_set_qkey drivers/infiniband/core/cma.c:510 [inline] BUG: KMSAN: uninit-value in cma_make_mc_event+0xb73/0xe00 drivers/infiniband/core/cma.c:4570 cma_set_qkey drivers/infiniband/core/cma.c:510 [inline] cma_make_mc_event+0xb73/0xe00 drivers/infiniband/core/cma.c:4570 cma_iboe_join_multicast drivers/infiniband/core/cma.c:4782 [inline] rdma_join_multicast+0x2b83/0x30a0 drivers/infiniband/core/cma.c:4814 ucma_process_join+0xa76/0xf60 drivers/infiniband/core/ucma.c:1479 ucma_join_multicast+0x1e3/0x250 drivers/infiniband/core/ucma.c:1546 ucma_write+0x639/0x6d0 drivers/infiniband/core/ucma.c:1732 vfs_write+0x8ce/0x2030 fs/read_write.c:588 ksys_write+0x28c/0x520 fs/read_write.c:643 __do_sys_write fs/read_write.c:655 [inline] __se_sys_write fs/read_write.c:652 [inline] __ia32_sys_write+0xdb/0x120 fs/read_write.c:652 do_syscall_32_irqs_on arch/x86/entry/common.c:114 [inline] __do_fast_syscall_32+0x96/0xf0 arch/x86/entry/common.c:180 do_fast_syscall_32+0x34/0x70 arch/x86/entry/common.c:205 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:248 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c Local variable ib.i created at: cma_iboe_join_multicast drivers/infiniband/core/cma.c:4737 [inline] rdma_join_multicast+0x586/0x30a0 drivers/infiniband/core/cma.c:4814 ucma_process_join+0xa76/0xf60 drivers/infiniband/core/ucma.c:1479 CPU: 0 PID: 29874 Comm: syz-executor.3 Not tainted 5.16.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ===================================================== [1] https://lore.kernel.org/linux-rdma/20220117183832.GD84788@nvidia.com/
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Linux | Kernel | 5.10.0 | 5.10.178 |
| SUSE:Linux Enterprise High Availability Extension 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-64kb | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-default | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-default-base | 0 | 5.14.21-150400.24.179.1.150400.24.92.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-docs | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-obs-build | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-source | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-syms | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-64kb | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default-base | 0 | 5.14.21-150400.24.179.1.150400.24.92.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-docs | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-obs-build | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-source | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-syms | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-64kb | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-default | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-default-base | 0 | 5.14.21-150500.55.124.1.150500.6.59.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-docs | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-obs-build | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-source | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-syms | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-64kb | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-default | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-default-base | 0 | 5.14.21-150500.55.124.1.150500.6.59.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-docs | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-obs-build | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-source | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-syms | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Live Patching 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Live Patching 15 SP4 | kernel-livepatch-SLE15-SP4_Update_45 | 0 | 1-150400.9.3.1 |
| SUSE:Linux Enterprise Live Patching 15 SP5 | kernel-default | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Live Patching 15 SP5 | kernel-livepatch-SLE15-SP5_Update_31 | 0 | 1-150500.11.3.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-default | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-default-base | 0 | 5.14.21-150400.24.179.1.150400.24.92.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-rt | 0 | 5.14.21-150400.15.133.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-source-rt | 0 | 5.14.21-150400.15.133.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-default | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-default-base | 0 | 5.14.21-150400.24.179.1.150400.24.92.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-rt | 0 | 5.14.21-150400.15.133.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-source-rt | 0 | 5.14.21-150400.15.133.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-default | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-default-base | 0 | 5.14.21-150500.55.124.1.150500.6.59.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-rt | 0 | 5.14.21-150500.13.109.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-source | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-source-rt | 0 | 5.14.21-150500.13.109.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-64kb | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-default | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-default-base | 0 | 5.14.21-150400.24.179.1.150400.24.92.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-docs | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-obs-build | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-source | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-syms | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-zfcpdump | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Server 15 SP5-LTSS | kernel-64kb | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Server 15 SP5-LTSS | kernel-default | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Server 15 SP5-LTSS | kernel-default-base | 0 | 5.14.21-150500.55.124.1.150500.6.59.1 |
| SUSE:Linux Enterprise Server 15 SP5-LTSS | kernel-docs | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Server 15 SP5-LTSS | kernel-obs-build | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Server 15 SP5-LTSS | kernel-source | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Server 15 SP5-LTSS | kernel-syms | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Server 15 SP5-LTSS | kernel-zfcpdump | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default-base | 0 | 5.14.21-150400.24.179.1.150400.24.92.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-docs | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-obs-build | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-source | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-syms | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | kernel-default | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | kernel-default-base | 0 | 5.14.21-150500.55.124.1.150500.6.59.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | kernel-docs | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | kernel-obs-build | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | kernel-source | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | kernel-syms | 0 | 5.14.21-150500.55.124.1 |
| SUSE:Manager Proxy LTS 4.3 | kernel-default | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Manager Proxy LTS 4.3 | kernel-default-base | 0 | 5.14.21-150400.24.179.1.150400.24.92.1 |
| SUSE:Manager Proxy LTS 4.3 | kernel-source | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Manager Proxy LTS 4.3 | kernel-syms | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Manager Server LTS 4.3 | kernel-default | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Manager Server LTS 4.3 | kernel-default-base | 0 | 5.14.21-150400.24.179.1.150400.24.92.1 |
| SUSE:Manager Server LTS 4.3 | kernel-source | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Manager Server LTS 4.3 | kernel-syms | 0 | 5.14.21-150400.24.179.1 |
| SUSE:Manager Server LTS 4.3 | kernel-zfcpdump | 0 | 5.14.21-150400.24.179.1 |
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