CVE-2026-64541
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk42th percentile - higher than 42% of all known CVEs
Summary
A use-after-free (UAF) vulnerability was found in the Linux kernel's smc_cdc_rx_handler() function for the SMC-R protocol. The issue occurs because no socket reference is held after releasing the conns_lock, allowing a concurrent close() to free memory before sock_hold() is called.
Risk Assessment
An attacker could trigger a kernel panic or potentially escalate privileges by exploiting the freed memory. This affects systems using SMC-R (Shared Memory Communications over RDMA).
Recommendation
Apply the Linux kernel patch that holds a socket reference (sock_hold) before releasing the conns_lock. Update to a kernel version containing this fix immediately.
Other vulnerabilities in Linux kernel
See all- CVE-2026-90049Unknown
In the Linux kernel, a vulnerability in skb_zerocopy() was fixed: it incorrectly called skb_tx_error() on the source skb when copying frags. This completed the zerocopy uarg and cleared the SKBFL_SHARED_FRAG flag on an skb still in use by the network stack. Specifically on the OVS_ACTION_ATTR_USERSPACE path, the skb was not freed on error, which could lead to ESP data being decrypted in place where the skb did not privately own frags, potentially causing data corruption or other issues.
- CVE-2026-90046Unknown
In the Linux kernel, free_pages_nolock() uses spin_trylock() in NMI context on uniprocessor (UP) systems, which is unsafe. The bug affects the page freeing path and can crash the kernel. It is likely exploitable by local attackers for privilege escalation.
- CVE-2026-90045Unknown
In the Linux kernel USB gadget ffs driver, the io_data structure stores a pointer to the submitting task's mm_struct but does not hold a reference while async requests are pending. This can cause a use-after-free if the task exits before completion handling finishes. The fix takes a reference with mmgrab() when queuing and releases it with mmdrop() on completion.
- CVE-2026-90044Unknown
In the Linux kernel USB gadget f_fs driver, a use-after-free exists in the AIO error path. When ffs_epfile_io() fails with an error other than -EIOCBQUEUED, the io_data structure is freed, but the kiocb cancel function remains armed and points to the freed pointer. A concurrent cancel (e.g., sys_io_cancel()) can cause a use-after-free. The fix safely disarms the cancellation via kiocb->ki_complete() and returns -EIOCBQUEUED.
- CVE-2026-90043Unknown
In the Linux kernel zram module, the slot lock bit is set in the wrong position on 64-bit big-endian systems. Instead of landing in the flags field, it lands in ac_time, so with ZRAM_TRACK_ENTRY_ACTIME enabled, storing the access time wipes out the held lock bit and lets another CPU take the same slot lock. An access time value with that bit set can make the slot appear locked forever. The fix shifts the lock bit into the flags half on big-endian 64-bit.
- CVE-2026-90042Unknown
A vulnerability was found in the Linux kernel's Ceph filesystem where ceph_fname_to_usr() passed vmalloc() buffers to the fscrypt crypto API, which requires linear memory. This can cause kernel oopses, especially on non-x86 platforms. The fix adds support for vmalloc() buffers using a bounce buffer.
- CVE-2026-90041Unknown
In the Linux kernel, the HID sony driver fails to remove a controller from the device list when HID core input device registration fails. The devres-managed sony_sc is freed while its list node remains linked, leading to use-after-free when the next matching controller is handled.
- CVE-2026-90039Unknown
In the Linux kernel, NFSD admin state-revocation handlers (unlock_filesystem, NFSD_CMD_UNLOCK_FILESYSTEM, NFSD_CMD_UNLOCK_EXPORT) only check nn->nfsd_serv, which is set before nn->conf_id_hashtbl is allocated. This leads to a NULL dereference when the server has not yet started.
- CVE-2026-90038Unknown
In the Linux kernel, nfsd4_revoke_export_states() drops nn->client_lock but the held stateid reference does not pin the client. A concurrent client teardown can free the client while revoke_one_stid() still dereferences it, causing a use-after-free.
- CVE-2026-90037Unknown
In the Linux kernel, an nfs4_openowner left on nn->close_lru holds only a raw pointer to its nfs4_client. When the laundromat reaps entries, drops client_lock and calls nfs4_put_stid(), a concurrent force_expire_client() can free the client, causing a use-after-free.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: net/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket smc_cdc_rx_handler() looks up the connection by token under the link group's conns_lock, drops the lock, and then dereferences conn and the smc_sock derived from it, ending in sock_hold(&smc->sk) inside smc_cdc_msg_recv(). No reference is held across the lock release. The only reference pinning the socket while the connection is discoverable in the link group is taken in smc_lgr_register_conn() (sock_hold) and dropped in __smc_lgr_unregister_conn() (sock_put), both under conns_lock. Once the handler drops conns_lock, a concurrent close() -> smc_release() -> smc_conn_free() -> smc_lgr_unregister_conn() can drop that reference and free the smc_sock, so the handler's later sock_hold() runs on freed memory: WARNING: lib/refcount.c:25 at refcount_warn_saturate Workqueue: rxe_wq do_work refcount_warn_saturate (lib/refcount.c:25) smc_cdc_msg_recv (net/smc/smc_cdc.c:430) smc_cdc_rx_handler (net/smc/smc_cdc.c:502) smc_wr_rx_tasklet_fn (net/smc/smc_wr.c:445) tasklet_action_common (kernel/softirq.c:938) handle_softirqs (kernel/softirq.c:622) Kernel panic - not syncing: panic_on_warn set Only SMC-R is affected. The SMC-D receive tasklet is stopped by tasklet_kill(&conn->rx_tsklet) in smc_conn_free() before the connection is unregistered, so it cannot run concurrently with the free. Take the socket reference while still holding conns_lock, so the registration reference can no longer be the last one, and drop it once the handler is done.