CVE-2025-23138: watch_queue: fix pipe accounting mismatch

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-04-16 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: watch_queue: fix pipe accounting mismatch Currently, watch_queue_set_size() modifies the pipe buffers charged to user->pipe_bufs without updating the pipe->nr_accounted on the pipe itself, due to the if (!pipe_has_watch_queue()) test in pipe_resize_ring(). This means that when the pipe is ultimately freed, we decrement user->pipe_bufs by something other than what than we had charged to it, potentially leading to an underflow. This in turn can cause subsequent too_many_pipe_buffers_soft() tests to fail with -EPERM. To remedy this, explicitly account for the pipe usage in watch_queue_set_size() to match the number set via account_pipe_buffers() (It's unclear why watch_queue_set_size() does not update nr_accounted; it may be due to intentional overprovisioning in watch_queue_set_size()?)

Affected products

Debian Linux: 11.0
Linux kernel: from 5.10.210 before 5.10.236; from 5.15.149 before 5.15.180; from 6.1.76 before 6.1.134; from 6.6.15 before 6.6.87; from 6.7.3 before 6.12.23; from 6.13 before 6.13.11 — fixed in 5.10.236, 5.15.180, 6.1.134, 6.12.23, 6.13.11, 6.14.2

How to fix

Upgrade to a fixed version: Linux kernel 5.10.236, 5.15.180, 6.1.134, 6.12.23. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2025-23138 or the next vulnerability affects your stack