Linux Distros Unpatched Vulnerability : CVE-2026-99254

critical Nessus Plugin ID 375585

Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

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

- io_uring: don't flood a cancelling task with task_work io_ring_exit_work() asks each task which has used the ring to remove its tctx node, by task_work, and repeats that until the list is empty.
io_tctx_exit_cb() doesn't touch the node while the task is in io_uring_cancel_generic(), which removes all the nodes at its end. So the work item queues the callback again as soon as it has completed, for nothing.
That is more than a waste of time. task_work_run() only returns when it finds the list empty. If the rings are released from inside the cancellation, because requests of other rings held the last references to their files, up to 64 work items keep sending callbacks to the one task which is running them. It never finds the list empty, never gets back to the cancellation, the nodes stay, and so it goes on: a task with 60 pairs of rings which poll each other ran 280000 callbacks in 5 seconds, 20 seconds after exit_group().
It ends when all the senders happen to be late at the same time. Until then the task keeps a CPU and the work items busy. An exiting task can't be killed meanwhile. execve() cancels the requests in the same way, so a live task can get stuck there as well, for minutes. If it takes more than five, the work items run into the WARN_ON_ONCE(time_after(jiffies, timeout)) of io_ring_exit_work(). No privilege is needed for any of this. If the callback has met a task in cancellation, wait a little before it is sent again. Nobody has to wake the work item up for that: either the node is gone by then, or it is the turn of the next round.
(CVE-2026-99254)

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

Solution

There is no known solution at this time.

Plugin Details

Severity: Critical

ID: 375585

File Name: unpatched_CVE_2026_99254.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Misc.

Published: 11/3/2026

Updated: 11/3/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.74

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS Score Source: CVE-2026-99254

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 9

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:U/RC:C

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:12.0, cpe:/o:debian:debian_linux:14.0, p-cpe:/a:debian:debian_linux:linux

Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 11/3/2026

Reference Information

CVE: CVE-2026-99254

Detections

Analytics