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CVE-2026-53321: io_uring/napi: cap busy_poll_to 10 msec

• 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: 2026-06-26 · updated 2026-10-21

Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/napi: cap busy_poll_to 10 msec Currently there's no cap on the maximum amount of time that napi is allowed to poll if no events are found, which can lead to kernel complaints on a task being stuck as there's no conditional rescheduling done within that loop. Just cap it to 10 msec in total, that's already way above any kind of sane value that will reap any benefits, yet low enough that it's nowhere near being able to trigger preemption complaints.

Affected products

• Linux kernel: from 6.9 before 6.18.33; from 6.19 before 7.0.10; 7.1-rc1 — fixed in 6.18.33, 7.0.10

How to fix

Upgrade to a fixed version: Linux kernel 6.18.33, 7.0.10. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/39767f944a8c9e696566c37ad5b20131406c4b8d
• https://git.kernel.org/stable/c/42785efe813e5a7d815f3b6be126e1bc0d12d2b6
• https://git.kernel.org/stable/c/cb3af525f8dfb8930f0c123e5755fa967a12d5c1
• https://git.kernel.org/stable/c/df8599ee18c0e5fe343ffe0b4c379636b8bb839a

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