critical CVSS 9.8 EPSS <0.1%

CVE-2022-49407·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: dlm: fix plock invalid read This patch fixes an invalid read showed by KASAN. A unlock will allocate a "struct plock_op" and a followed send_op() will append it to a global send_list data structure. In some cases a followed dev_read() moves it to recv_list and dev_write() will cast it to "struct plock_xop" and access fields which are only available in those structures. At this point an invalid read happens by accessing those fields. To fix this issue the "callback" field is moved to "struct plock_op" to indicate that a cast to "plock_xop" is allowed and does the additional "plock_xop" handling if set. Example of the KASAN output which showed the invalid read: [ 2064.296453] ================================================================== [ 2064.304852] BUG: KASAN: slab-out-of-bounds in dev_write+0x52b/0x5a0 [dlm] [ 2064.306491] Read of size 8 at addr ffff88800ef227d8 by task dlm_controld/7484 [ 2064.308168] [ 2064.308575] CPU: 0 PID: 7484 Comm: dlm_controld Kdump: loaded Not tainted 5.14.0+ #9 [ 2064.310292] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 [ 2064.311618] Call Trace: [ 2064.312218] dump_stack_lvl+0x56/0x7b [ 2064.313150] print_address_description.constprop.8+0x21/0x150 [ 2064.314578] ? dev_write+0x52b/0x5a0 [dlm] [ 2064.315610] ? dev_write+0x52b/0x5a0 [dlm] [ 2064.316595] kasan_report.cold.14+0x7f/0x11b [ 2064.317674] ? dev_write+0x52b/0x5a0 [dlm] [ 2064.318687] dev_write+0x52b/0x5a0 [dlm] [ 2064.319629] ? dev_read+0x4a0/0x4a0 [dlm] [ 2064.320713] ? bpf_lsm_kernfs_init_security+0x10/0x10 [ 2064.321926] vfs_write+0x17e/0x930 [ 2064.322769] ? __fget_light+0x1aa/0x220 [ 2064.323753] ksys_write+0xf1/0x1c0 [ 2064.324548] ? __ia32_sys_read+0xb0/0xb0 [ 2064.325464] do_syscall_64+0x3a/0x80 [ 2064.326387] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 2064.327606] RIP: 0033:0x7f807e4ba96f [ 2064.328470] Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 39 87 f8 ff 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 7c 87 f8 ff 48 [ 2064.332902] RSP: 002b:00007ffd50cfe6e0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 [ 2064.334658] RAX: ffffffffffffffda RBX: 000055cc3886eb30 RCX: 00007f807e4ba96f [ 2064.336275] RDX: 0000000000000040 RSI: 00007ffd50cfe7e0 RDI: 0000000000000010 [ 2064.337980] RBP: 00007ffd50cfe7e0 R08: 0000000000000000 R09: 0000000000000001 [ 2064.339560] R10: 000055cc3886eb30 R11: 0000000000000293 R12: 000055cc3886eb80 [ 2064.341237] R13: 000055cc3886eb00 R14: 000055cc3886f590 R15: 0000000000000001 [ 2064.342857] [ 2064.343226] Allocated by task 12438: [ 2064.344057] kasan_save_stack+0x1c/0x40 [ 2064.345079] __kasan_kmalloc+0x84/0xa0 [ 2064.345933] kmem_cache_alloc_trace+0x13b/0x220 [ 2064.346953] dlm_posix_unlock+0xec/0x720 [dlm] [ 2064.348811] do_lock_file_wait.part.32+0xca/0x1d0 [ 2064.351070] fcntl_setlk+0x281/0xbc0 [ 2064.352879] do_fcntl+0x5e4/0xfe0 [ 2064.354657] __x64_sys_fcntl+0x11f/0x170 [ 2064.356550] do_syscall_64+0x3a/0x80 [ 2064.358259] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 2064.360745] [ 2064.361511] Last potentially related work creation: [ 2064.363957] kasan_save_stack+0x1c/0x40 [ 2064.365811] __kasan_record_aux_stack+0xaf/0xc0 [ 2064.368100] call_rcu+0x11b/0xf70 [ 2064.369785] dlm_process_incoming_buffer+0x47d/0xfd0 [dlm] [ 2064.372404] receive_from_sock+0x290/0x770 [dlm] [ 2064.374607] process_recv_sockets+0x32/0x40 [dlm] [ 2064.377290] process_one_work+0x9a8/0x16e0 [ 2064.379357] worker_thread+0x87/0xbf0 [ 2064.381188] kthread+0x3ac/0x490 [ 2064.383460] ret_from_fork+0x22/0x30 [ 2064.385588] [ 2064.386518] Second to last potentially related work creation: [ 2064.389219] kasan_save_stack+0x1c/0x40 [ 2064.391043] __kasan_record_aux_stack+0xaf/0xc0 [ 2064.393303] call_rcu+0x11b/0xf70 [ 2064.394885] dlm_process_incoming_buffer+0x47d/0xfd0 [dlm] [ 2064.397694] receive_from_sock+0x290/0x770 ---truncated---

Severity
critical
Software
Kernel
Fixed in
5.18.3
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at <0.1% — higher than 7% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2022-49407 scores 9.8 on CVSS, so a successful attack would be serious — but at <0.1%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

From: 5.18

Until: 5.18.3

Fixed in: 5.18.3

How to fix this CVE

Update your Linux kernel to version 5.18.3 or later to patch a memory safety issue in the DLM (Distributed Lock Manager) subsystem. The vulnerability allows invalid memory reads when processing plock operations, which could lead to information disclosure or system crashes. Apply the kernel update through your distribution's package manager and reboot to activate the patched version.

sudo dnf update kernel kernel-devel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Check your current kernel version: uname -r
  2. Verify if kernel version is between 5.18.0 and 5.18.2 (inclusive): uname -r | grep -E '5\.18\.[0-2]($|-)'
  3. Search system logs for KASAN errors related to dlm module: sudo grep -i 'kasan.*dlm\|dev_write.*dlm' /var/log/kern.log /var/log/syslog 2>/dev/null
  4. Confirm the fix by verifying kernel version is 5.18.3 or higher: uname -r | grep -E '5\.18\.[3-9]|5\.[1-9][0-9]\.|[6-9]\.[0-9]' && echo 'Patched' || echo 'Vulnerable'

FAQ

What is CVE-2022-49407?

CVE-2022-49407 is a memory safety vulnerability in the Linux kernel's DLM (Distributed Lock Manager) plock implementation. The bug occurs when the kernel incorrectly casts and accesses memory structures, leading to out-of-bounds reads that KASAN (Kernel Address Sanitizer) can detect.

Is CVE-2022-49407 being actively exploited?

No, CVE-2022-49407 is not listed on the CISA KEV catalog and no public exploits are currently available. However, it is a high-severity memory access violation that should be patched promptly to prevent potential information disclosure.

What versions of Kernel are affected by CVE-2022-49407?

Linux kernel versions 5.18.0 through 5.18.2 are affected. The vulnerability was resolved in kernel version 5.18.3 and later.

How do I check if my server is vulnerable to CVE-2022-49407?

Run 'uname -r' to display your kernel version. If the output shows 5.18.0, 5.18.1, or 5.18.2, your system is vulnerable and requires immediate kernel update and reboot.

Does Defensia detect CVE-2022-49407?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2022-49407 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2026-63795CVSS 10In the Linux kernel, the following vulnerability has been resolved: 9p: avoid putting oldfid in p9_client_walk() error path When p9_client_walk() is called with clone set to false, fid aliases oldfid. If the walk subsequently fails after the request has been sent, the error path jumps to clunk_fid, which currently calls p9_fid_put(fid) unconditionally. This drops a reference to oldfid even though ownership of oldfid remains with the caller. If this is the last reference, oldfid can be clunked and destroyed while the caller still expects it to be valid. A later use or put of oldfid can then trigger a use-after-free or refcount underflow. Fix this by only putting fid in the clunk_fid error path when it does not alias oldfid, matching the existing guard in the error path below. This can be triggered when a multi-component walk is split into multiple p9_client_walk() calls and a later non-cloning walk fails. A reproducer and refcount warning logs are available on request.
CVE-2026-98365CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: Fix integer overflow in mr_check_range() leading to OOB access mr_check_range() validates that [iova, iova+length) falls within the registered MR range using wraparound-prone arithmetic: if (iova < mr->ibmr.iova || iova + length > mr->ibmr.iova + mr->ibmr.length) A remote peer can craft an RDMA-Write/Read RETH so that iova + length wraps to 0 (e.g. iova=0xfffffffffffffff8, length=8), bypassing the check. rxe_mr_iova_to_index() then computes a huge index (int idx, only guarded by WARN_ON) and rxe_mr_copy_xarray() dereferences mr->page_info[huge], causing an out-of-bounds read/write and a kernel oops that is triggerable by an unauthenticated remote peer. Rewrite the check in overflow-safe form; the first two clauses guarantee that the subsequent subtractions do not underflow: if (iova < mr->ibmr.iova || length > mr->ibmr.length || iova - mr->ibmr.iova > mr->ibmr.length - length) With the fix, mr_check_range() returns -EINVAL for the crafted iova and the responder reports REMOTE_ACCESS_ERROR instead of triggering the OOB.
CVE-2026-53399CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: nfsd: release layout stid on setlease failure nfs4_alloc_stid() publishes the new stid into cl->cl_stateids via idr_alloc_cyclic() under cl_lock before returning to nfsd4_alloc_layout_stateid(). When nfsd4_layout_setlease() then fails, the error path frees the layout stateid directly with kmem_cache_free() without ever calling idr_remove(), leaving the IDR slot pointing at freed slab memory. Any subsequent IDR walker (states_show, client teardown) dereferences the dangling pointer. The correct teardown for an IDR-published stid is nfs4_put_stid(), which removes the IDR slot under cl_lock, dispatches sc_free (nfsd4_free_layout_stateid) to release ls->ls_file via nfsd4_close_layout(), and drops the nfs4_file reference in its tail. A second issue blocks that switch: nfsd4_free_layout_stateid() unconditionally inspects ls->ls_fence_work via delayed_work_pending() under ls_lock, but INIT_DELAYED_WORK(&ls->ls_fence_work, ...) currently runs only after the setlease call. On the setlease-failure path the destructor would touch an uninitialized delayed_work. nfsd4_alloc_layout_stateid() nfs4_alloc_stid() /* idr_alloc_cyclic under cl_lock */ nfsd4_layout_setlease() /* fails */ nfs4_put_stid() nfsd4_free_layout_stateid() delayed_work_pending(&ls->ls_fence_work) /* needs INIT */ nfsd4_close_layout() /* nfsd_file_put(ls->ls_file) */ put_nfs4_file() Fix by hoisting the ls_fenced / ls_fence_delay / INIT_DELAYED_WORK initialization above the nfsd4_layout_setlease() call, and replace the manual nfsd_file_put + put_nfs4_file + kmem_cache_free cleanup with a single nfs4_put_stid(stp).
CVE-2026-53398CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix SECINFO_NO_NAME decode error cleanup nfsd4_decode_secinfo_no_name() currently initializes sin_exp after decoding sin_style. If the XDR stream is truncated, the decoder returns nfserr_bad_xdr before sin_exp is initialized. Since commit 3fdc54646234 ("NFSD: Reduce amount of struct nfsd4_compoundargs that needs clearing"), the inline iops array is not cleared between RPC calls. A failed SECINFO_NO_NAME decode can therefore leave sin_exp holding stale union contents from a previous operation. The error response path still invokes nfsd4_secinfo_no_name_release(), which calls exp_put() on a non-NULL sin_exp. Initialize sin_exp before the first failable decode step, matching nfsd4_decode_secinfo().
CVE-2026-98548CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: sctp: discard the rest of the packet on a stale-cookie error When an association is in COOKIE-ECHOED state and the peer sends a bundled [ERROR(Stale Cookie)][DATA] packet from one of its non-primary addresses, processing the ERROR chunk takes the non-fatal stale-cookie retry path sctp_sf_do_5_2_6_stale(), which queues SCTP_CMD_DEL_NON_PRIMARY while keeping the association alive. sctp_cmd_del_non_primary() removes every non-primary transport - including the very transport this packet arrived on, which is still referenced by the receive lookup and shared by all chunks of the packet via chunk->transport. sctp_assoc_rm_peer() does redirect asoc->peer.last_data_from away from the removed transport, but right afterwards the bundled DATA chunk makes sctp_assoc_bh_rcv() re-register asoc->peer.last_data_from = chunk->transport unconditionally, undoing the redirection with the just-removed transport. Once the packet is done, the receive reference is dropped and the transport is RCU-freed, while the surviving association keeps the dangling last_data_from. A later FWD-TSN (or the delayed SACK timer) makes sctp_gen_sack() dereference it (->param_flags and friends), and sctp_make_sack()/sctp_outq_select_transport() may write to the freed object and link it into the live transport list. This is a use-after-free triggerable by any malicious SCTP peer (or a local unprivileged user acting as one) with no capabilities required: BUG: KASAN: slab-use-after-free in sctp_do_sm+0x498a/0x5660 Read of size 4 at addr ffff88800e1e356c by task poc/115 Call Trace: sctp_do_sm <- sctp_assoc_bh_rcv <- sctp_inq_push <- sctp_rcv <- ip_protocol_deliver_rcu <- ip_rcv Allocated: sctp_transport_new <- sctp_assoc_add_peer <- sctp_process_init (INIT-ACK processing) Freed: kfree <- sctp_transport_destroy_rcu <- rcu_core (call_rcu queued by sctp_transport_put at end of sctp_rcv) The buggy address is located 364 bytes inside of freed 1024-byte region [ffff88800e1e3400, ffff88800e1e3800), cache kmalloc-1k Note that commit 03a9d10ecf71 ("sctp: drop a chunk if its transport was removed") only covers the window between the receive lookup and the chunk processing (e.g. an ASCONF DEL-IP racing the socket backlog); here the transport is removed *while* the packet is being processed, by an earlier chunk of the same packet, so the drop in sctp_inq_push() does not reach this path. Verified with the bundled [ERROR(Stale Cookie)][DATA] + FWD-TSN reproducer: the KASAN report above still fires with that commit applied, and is gone with this patch on top. Fix it by discarding the rest of the packet on this path, as suggested by Xin. After the stale-cookie ERROR has sent the association back to COOKIE-WAIT and removed the non-primary transports, the remaining chunks of the packet can only run against the restarted handshake while referencing the removed arrival transport through chunk->transport: besides the last_data_from registration above, sctp_cmd_setup_t2() and the sctp_make_*() reply builders would also copy that pointer into association-lifetime state that sctp_assoc_rm_peer() has already sanitized. Let the peer retransmit them, in line with what sctp_inq_push() does for chunks whose transport was removed before processing.

References

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