# CVE-2026-74290: net/sched: cls_flow: Dont expose folded kernel pointers

> A local attacker with network namespace privileges can recover folded kernel pointers via the flow classifier, leading to information disclosure.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-74290, DEBIAN-CVE-2026-74290, GHSA-wfqw-582v-82vh, UBUNTU-CVE-2026-74290

## What is CVE-2026-74290?

CVE-2026-74290 is a vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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)

## Which versions are affected by CVE-2026-74290?


## How do I fix CVE-2026-74290?

Apply the vendor's patch.

## Is CVE-2026-74290 being exploited?

There is no known exploitation of CVE-2026-74290 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74290 and fix it if it is affected.

What it is: CVE-2026-74290 is a vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-74290 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-74290/ (Markdown: https://insights.sbomify.com/CVE-2026-74290/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74290
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74290
- OSV: https://osv.dev/vulnerability/CVE-2026-74290

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74290/
Summaries are generated and may contain mistakes; the official description above is the record.