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Echo: linux: security update to 6.1.176-1

high Tenable Cloud Security Plugin ID 455621

Description

There are packages installed that are affected by a vulnerability referenced in the following CVE:

 - In the Linux kernel, the following vulnerability has been resolved: fs/fcntl: fix SOFTIRQ-unsafe lock
 order in fasync signaling A SOFTIRQ-safe to SOFTIRQ-unsafe lock order deadlock can occur in send_sigio()
 and send_sigurg() when a process group receives a signal. When FASYNC is configured for a process group
 (PIDTYPE_PGID), both functions use read_lock(&tasklist_lock) to traverse the task list. However, they are
 frequently called from softirq context: - send_sigio() via input_inject_event -> kill_fasync -
 send_sigurg() via tcp_check_urg -> sk_send_sigurg (NET_RX_SOFTIRQ) The deadlock is caused by the rwlock
 writer fairness mechanism: 1. CPU 0 (process context) holds read_lock(&tasklist_lock) in do_wait(). 2. CPU
 1 (process context) attempts write_lock(&tasklist_lock) in fork() or exit() and spins, which blocks all
 new readers. 3. CPU 0 is interrupted by a softirq (e.g., TCP URG packet reception). 4. The softirq calls
 send_sigurg() and attempts to acquire read_lock(&tasklist_lock), deadlocking because CPU 1 is waiting.
 Since PID hashing and do_each_pid_task() traversals are already RCU-protected, the read_lock on
 tasklist_lock is no longer strictly required for safe traversal. Fix this by replacing tasklist_lock with
 rcu_read_lock(), aligning the process group signaling path with the single-PID path. This also mitigates a
 potential remote denial of service vector via TCP URG packets. Lockdep splat:
 ===================================================== WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order
 detected [...] Chain exists of: &dev->event_lock --> &f_owner->lock --> tasklist_lock Possible interrupt
 unsafe locking scenario: CPU0 CPU1 ---- ---- lock(tasklist_lock); local_irq_disable();
 lock(&dev->event_lock); lock(&f_owner->lock); <Interrupt> lock(&dev->event_lock); *** DEADLOCK ***
 (CVE-2026-52946)

Solution

Update the linux library and its related packages to version 6.1.176-1 or later.

See Also

https://advisory.echohq.com/cve/CVE-2026-52946

Plugin Details

Severity: High

ID: 455621

Version: Revision 1.1

Type: Local

Published: 10/1/2026

Updated: 10/1/2026

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.6

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 5.8

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

CVSS Score Source: CVE-2026-52946

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

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

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

Vulnerability Information

Exploit Ease: No known exploits are available

Patch Publication Date: 6/25/2026

Vulnerability Publication Date: 6/24/2026

Reference Information

CVE: CVE-2026-52946