In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: avoid stale FIFO cells during resize snd_seq_fifo_resize() still needs to publish the replacement pool before it waits for FIFO users. A blocking snd_seq_read() holds f->use_lock while it sleeps, so concurrent senders must be able to queue to the new pool and wake that reader instead of failing against a closing old pool. However, snd_seq_fifo_event_in() duplicates an event before it takes f->lock, and snd_seq_read() can dequeue a cell and later call snd_seq_fifo_cell_putback() if copy_to_user() or snd_seq_expand_var_event() fails. If resize swaps f->pool and detaches oldhead in between, either path can relink an old-pool cell after the snapshot. That stale cell sits outside the drained oldhead list, keeps oldpool->counter elevated, and can leave snd_seq_pool_delete() waiting for the retired pool to drain. Keep the existing swap-before-wait ordering in snd_seq_fifo_resize(), but reject stale cells before any FIFO relink. Revalidate event-in cells under f->lock and retry them against the published replacement pool, and free stale putback cells instead of linking them back into the FIFO. The buggy scenario involves two paths, with each column showing the order within that path: resize path: relink path: 1. Allocate newpool. 1. Take f->use_lock. 2. Swap f->pool to newpool and 2. Duplicate or dequeue an old-pool detach oldhead. cell before oldpool closes. 3. Mark oldpool closing and 3. Reach a later relink point after wait for FIFO users. resize published newpool. 4. Free oldhead and delete 4. Relink the old-pool cell after oldpool. resize detached oldhead. 5. Drop f->use_lock. The reproducer reports a resize ioctl blocked in the expected pool teardown path: signal: resize iteration=98 target_pool=4 exceeded 250ms (elapsed=251ms) diagnostic: resize_tid=651 wchan=snd_seq_pool_done diagnostic: resize_tid=651 stack= snd_seq_pool_done+0x5b/0x140 snd_seq_pool_delete+0x7a/0x90 snd_seq_fifo_resize+0x193/0x1e0 snd_seq_ioctl_set_client_pool+0x214/0x260 snd_seq_ioctl+0x119/0x540 __x64_sys_ioctl+0xd1/0x120 do_syscall_64+0xbb/0x2f0 entry_SYSCALL_64_after_hwframe+0x77/0x7f A second run with larger pools hit the same target path: signal: resize iteration=32 target_pool=64 exceeded 250ms (elapsed=251ms) diagnostic: resize_tid=663 wchan=snd_seq_pool_done diagnostic: resize_tid=663 stack= snd_seq_pool_done+0x5b/0x140 snd_seq_pool_delete+0x7a/0x90 snd_seq_fifo_resize+0x193/0x1e0 snd_seq_ioctl_set_client_pool+0x214/0x260 snd_seq_ioctl+0x119/0x540 __x64_sys_ioctl+0xd1/0x120 do_syscall_64+0xbb/0x2f0 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - ALSA: seq: avoid stale FIFO cells during resize snd_seq_fifo_resize() still needs to publish the     replacement pool before it waits for FIFO users. A blocking snd_seq_read() holds f->use_lock while it     sleeps, so concurrent senders must be able to queue to the new pool and wake that reader instead of     failing against a closing old pool. However, snd_seq_fifo_event_in() duplicates an event before it takes     f->lock, and snd_seq_read() can dequeue a cell and later call snd_seq_fifo_cell_putback() if     copy_to_user() or snd_seq_expand_var_event() fails. If resize swaps f->pool and detaches oldhead in     between, either path can relink an old-pool cell after the snapshot. That stale cell sits outside the     drained oldhead list, keeps oldpool->counter elevated, and can leave snd_seq_pool_delete() waiting for the     retired pool to drain. Keep the existing swap-before-wait ordering in snd_seq_fifo_resize(), but reject     stale cells before any FIFO relink. Revalidate event-in cells under f->lock and retry them against the     published replacement pool, and free stale putback cells instead of linking them back into the FIFO. The     buggy scenario involves two paths, with each column showing the order within that path: resize path:
    relink path: 1. Allocate newpool. 1. Take f->use_lock. 2. Swap f->pool to newpool and 2. Duplicate or     dequeue an old-pool detach oldhead. cell before oldpool closes. 3. Mark oldpool closing and 3. Reach a     later relink point after wait for FIFO users. resize published newpool. 4. Free oldhead and delete 4.
    Relink the old-pool cell after oldpool. resize detached oldhead. 5. Drop f->use_lock. The reproducer     reports a resize ioctl blocked in the expected pool teardown path: signal: resize iteration=98     target_pool=4 exceeded 250ms (elapsed=251ms) diagnostic: resize_tid=651 wchan=snd_seq_pool_done     diagnostic: resize_tid=651 stack= snd_seq_pool_done+0x5b/0x140 snd_seq_pool_delete+0x7a/0x90     snd_seq_fifo_resize+0x193/0x1e0 snd_seq_ioctl_set_client_pool+0x214/0x260 snd_seq_ioctl+0x119/0x540
    __x64_sys_ioctl+0xd1/0x120 do_syscall_64+0xbb/0x2f0 entry_SYSCALL_64_after_hwframe+0x77/0x7f A second run     with larger pools hit the same target path: signal: resize iteration=32 target_pool=64 exceeded 250ms     (elapsed=251ms) diagnostic: resize_tid=663 wchan=snd_seq_pool_done diagnostic: resize_tid=663 stack=     snd_seq_pool_done+0x5b/0x140 snd_seq_pool_delete+0x7a/0x90 snd_seq_fifo_resize+0x193/0x1e0     snd_seq_ioctl_set_client_pool+0x214/0x260 snd_seq_ioctl+0x119/0x540 __x64_sys_ioctl+0xd1/0x120     do_syscall_64+0xbb/0x2f0 entry_SYSCALL_64_after_hwframe+0x77/0x7f (CVE-2026-74261)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
366742	SUSE SLED15: cluster-md-kmp-default / dlm-kmp-default / gfs2-kmp-default / etc (SUSE-SU-2026:4706-1)	Nessus	SuSE Local Security Checks	Local	high
365768	Ubuntu 26.04 LTS : Linux kernel (Azure) vulnerabilities (USN-8888-1)	Nessus	Ubuntu Local Security Checks	Local	medium
365767	Ubuntu 26.04 LTS : Linux kernel vulnerabilities (USN-8887-1)	Nessus	Ubuntu Local Security Checks	Local	medium
365463	Ubuntu 26.04 LTS : Linux kernel (OEM) vulnerabilities (USN-8889-1)	Nessus	Ubuntu Local Security Checks	Local	medium
350138	openSUSE 16: cluster-md-kmp-64kb / cluster-md-kmp-azure / cluster-md-kmp-default / etc (openSUSE-SU-2026:21910-1)	Nessus	SuSE Local Security Checks	Local	high
349185	SUSE SLES12: cluster-md-kmp-default / dlm-kmp-default / gfs2-kmp-default / etc (SUSE-SU-2026:4282-1)	Nessus	SuSE Local Security Checks	Local	high
335599	Linux Distros Unpatched Vulnerability : CVE-2026-74261	Nessus	Misc.	Local	low

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CVE-2026-74261

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