high CVSS 7.8 EPSS <0.1%

CVE-2024-26842·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: scsi: ufs: core: Fix shift issue in ufshcd_clear_cmd() When task_tag >= 32 (in MCQ mode) and sizeof(unsigned int) == 4, 1U << task_tag will out of bounds for a u32 mask. Fix this up to prevent SHIFT_ISSUE (bitwise shifts that are out of bounds for their data type). [name:debug_monitors&]Unexpected kernel BRK exception at EL1 [name:traps&]Internal error: BRK handler: 00000000f2005514 [#1] PREEMPT SMP [name:mediatek_cpufreq_hw&]cpufreq stop DVFS log done [name:mrdump&]Kernel Offset: 0x1ba5800000 from 0xffffffc008000000 [name:mrdump&]PHYS_OFFSET: 0x80000000 [name:mrdump&]pstate: 22400005 (nzCv daif +PAN -UAO) [name:mrdump&]pc : [0xffffffdbaf52bb2c] ufshcd_clear_cmd+0x280/0x288 [name:mrdump&]lr : [0xffffffdbaf52a774] ufshcd_wait_for_dev_cmd+0x3e4/0x82c [name:mrdump&]sp : ffffffc0081471b0 <snip> Workqueue: ufs_eh_wq_0 ufshcd_err_handler Call trace: dump_backtrace+0xf8/0x144 show_stack+0x18/0x24 dump_stack_lvl+0x78/0x9c dump_stack+0x18/0x44 mrdump_common_die+0x254/0x480 [mrdump] ipanic_die+0x20/0x30 [mrdump] notify_die+0x15c/0x204 die+0x10c/0x5f8 arm64_notify_die+0x74/0x13c do_debug_exception+0x164/0x26c el1_dbg+0x64/0x80 el1h_64_sync_handler+0x3c/0x90 el1h_64_sync+0x68/0x6c ufshcd_clear_cmd+0x280/0x288 ufshcd_wait_for_dev_cmd+0x3e4/0x82c ufshcd_exec_dev_cmd+0x5bc/0x9ac ufshcd_verify_dev_init+0x84/0x1c8 ufshcd_probe_hba+0x724/0x1ce0 ufshcd_host_reset_and_restore+0x260/0x574 ufshcd_reset_and_restore+0x138/0xbd0 ufshcd_err_handler+0x1218/0x2f28 process_one_work+0x5fc/0x1140 worker_thread+0x7d8/0xe20 kthread+0x25c/0x468 ret_from_fork+0x10/0x20

Severity
high
Software
Kernel
Fixed in
6.7.7
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 3% 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-2024-26842 scores 7.8 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: 6.7

Until: 6.7.7

Fixed in: 6.7.7

How to fix this CVE

Update your Linux kernel to version 6.7.7 or later to resolve a critical bitwise shift vulnerability in the UFS (Ultra Fast Storage) subsystem. This vulnerability affects multi-queue (MCQ) mode operations where task tags >= 32 cause out-of-bounds bit shifts in the ufshcd_clear_cmd() function, potentially triggering kernel panics. Apply the patch immediately on systems using UFS storage controllers.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your kernel version with `uname -r` and compare against 6.7.7 — versions 6.7.0 through 6.7.6 are vulnerable
  2. Step 2: Verify UFS subsystem is in use by running `lsmod | grep ufs` — if output appears, the affected driver is loaded
  3. Step 3: Search kernel logs for panic indicators with `dmesg | grep -i 'ufshcd_clear_cmd\|SHIFT_ISSUE\|BRK exception'` to identify past exploitation attempts
  4. Step 4: After patching, reboot the system with `sudo reboot` and confirm new kernel version with `uname -r` to verify the fix is active

FAQ

What is CVE-2024-26842?

CVE-2024-26842 is a kernel memory safety vulnerability in the Linux UFS storage driver where a bitwise shift operation exceeds the data type boundary when handling task tags in multi-queue mode (task_tag >= 32 on 32-bit systems). This triggers a kernel BRK exception and causes the system to panic.

Is CVE-2024-26842 being actively exploited?

No, CVE-2024-26842 is not listed in CISA's Known Exploited Vulnerabilities catalog and has no public exploit code available. However, it causes immediate kernel crashes on affected systems, making it a high-priority stability issue.

What versions of Kernel are affected by CVE-2024-26842?

Linux kernel versions 6.7.0 through 6.7.6 are vulnerable. The fix is included in kernel 6.7.7 and later stable releases.

How do I check if my server is vulnerable to CVE-2024-26842?

Run `uname -r` to get your kernel version. If it shows 6.7.0–6.7.6 and UFS storage is in use (check with `lsmod | grep ufs`), your system is vulnerable. Then run `sudo apt update && sudo apt install --only-upgrade linux-image-generic` (Ubuntu) or equivalent for your distro.

Does Defensia detect CVE-2024-26842?

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-2024-26842 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-2026-53260CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req(). syzbot reported a weird reqsk->rsk_refcnt underflow in __inet_csk_reqsk_queue_drop(). The captured reqsk_put() in __inet_csk_reqsk_queue_drop() is called only when it successfully removes reqsk from ehash. Moreover, reqsk_timer_handler() calls another reqsk_put() after that. This indicates that the reqsk was missing both refcnts for ehash and the timer itself. Since all the syzbot reports had PREEMPT_RT enabled, the only possible scenario is that reqsk_queue_hash_req() is preempted after mod_timer() and before refcount_set(), and then the timer triggered after 1s aborts the reqsk due to its listener's close(). Let's wrap mod_timer() and refcount_set() with preempt_disable_nested() and preempt_enable_nested(). Note that inet_ehash_insert() holds the normal spin_lock() (mutex in PREEMPT_RT), so it must be called outside of preempt_disable_nested(), but this is fine. The lookup path just ignores 0 sk_refcnt entries in ehash and tries to create another reqsk, but this will fail at inet_ehash_insert(). [0]: refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#0: ktimers/0/16 Modules linked in: CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28 Code: e4 7d d1 0a 67 48 0f b9 3a eb 4a e8 38 3d 23 fd 48 8d 3d e1 7d d1 0a 67 48 0f b9 3a eb 37 e8 25 3d 23 fd 48 8d 3d de 7d d1 0a <67> 48 0f b9 3a eb 24 e8 12 3d 23 fd 48 8d 3d db 7d d1 0a 67 48 0f RSP: 0000:ffffc90000157948 EFLAGS: 00010246 RAX: ffffffff84a1301b RBX: 0000000000000003 RCX: ffff88801ca98000 RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffffffff8f72ae00 RBP: ffffffff99ae3b01 R08: ffff88801ca98000 R09: 0000000000000005 R10: 0000000000000100 R11: 0000000000000004 R12: ffff8880425ef568 R13: ffff8880425ef4f8 R14: ffff8880425ef578 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888126386000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7b46710e9c CR3: 000000000dbb6000 CR4: 00000000003526f0 Call Trace: <TASK> __refcount_sub_and_test include/linux/refcount.h:400 [inline] __refcount_dec_and_test include/linux/refcount.h:432 [inline] refcount_dec_and_test include/linux/refcount.h:450 [inline] reqsk_put include/net/request_sock.h:136 [inline] __inet_csk_reqsk_queue_drop+0x3ce/0x440 net/ipv4/inet_connection_sock.c:1007 reqsk_timer_handler+0x651/0xdf0 net/ipv4/inet_connection_sock.c:1137 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2374 [inline] __run_timer_base+0x6a3/0x9f0 kernel/time/timer.c:2386 run_timer_base kernel/time/timer.c:2395 [inline] run_timer_softirq+0x67/0x170 kernel/time/timer.c:2403 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1151 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>
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-2026-53399CVSS 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-2026-53246CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: sctp: validate cached peer INIT chunk length in COOKIE_ECHO processing When a listening SCTP server processes a COOKIE_ECHO chunk, the cached peer INIT chunk embedded after the cookie is parsed and its parameters are later walked by sctp_process_init() using sctp_walk_params(). However, the chunk header length of this cached INIT chunk was not validated against the remaining buffer in the COOKIE_ECHO payload. If the length field is inflated, the parameter walk can run beyond the actual received data, leading to out-of-bounds reads and potential memory corruption during later parameter handling (e.g. STATE_COOKIE processing and kmemdup() copies). Add a bounds check in sctp_unpack_cookie() to ensure the cached INIT chunk length does not exceed the available data in the COOKIE_ECHO buffer before it is used.

References

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