# CVE-2025-38115: net_sched: sch_sfq: fix a potential crash on gso_skb handling

> A local attacker can cause a kernel crash in the SFQ network scheduler by triggering a null pointer dereference during GSO packet handling.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 3 Jul 2025
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-64580, BELL-CVE-2025-38115, DEBIAN-CVE-2025-38115, GHSA-9gqr-9337-3jr8, ROOT-OS-DEBIAN-11-CVE-2025-38115, ROOT-OS-DEBIAN-12-CVE-2025-38115, ROOT-OS-UBUNTU-2204-CVE-2025-38115, ROOT-OS-UBUNTU-2404-CVE-2025-38115, UBUNTU-CVE-2025-38115

## What is CVE-2025-38115?

CVE-2025-38115 is a high-severity vulnerability in Debian Debian Linux, published on 3 Jul 2025. 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: sch_sfq: fix a potential crash on gso_skb handling

SFQ has an assumption of always being able to queue at least one packet.

However, after the blamed commit, sch->q.len can be inflated by packets
in sch->gso_skb, and an enqueue() on an empty SFQ qdisc can be followed
by an immediate drop.

Fix sfq_drop() to properly clear q->tail in this situation.

ip netns add lb
ip link add dev to-lb type veth peer name in-lb netns lb
ethtool -K to-lb tso off                 # force qdisc to requeue gso_skb
ip netns exec lb ethtool -K in-lb gro on # enable NAPI
ip link set dev to-lb up
ip -netns lb link set dev in-lb up
ip addr add dev to-lb 192.168.20.1/24
ip -netns lb addr add dev in-lb 192.168.20.2/24
tc qdisc replace dev to-lb root sfq limit 100

ip netns exec lb netserver

netperf -H 192.168.20.2 -l 100 &
netperf -H 192.168.20.2 -l 100 &
netperf -H 192.168.20.2 -l 100 &
netperf -H 192.168.20.2 -l 100 &

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2025-38115?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-38115?

Apply the vendor's patch.

## Is CVE-2025-38115 being exploited?

There is no known exploitation of CVE-2025-38115 in the wild and no public exploit code.

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- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-38115 and fix it if it is affected.

What it is: CVE-2025-38115 is a high-severity vulnerability in Debian Debian Linux, published on 3 Jul 2025. 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-2025-38115 in the wild and no public exploit code.

Affected product: Debian Debian 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-2025-38115/ (Markdown: https://insights.sbomify.com/CVE-2025-38115/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38115
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38115
- OSV: https://osv.dev/vulnerability/CVE-2025-38115

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38115/
Summaries are generated and may contain mistakes; the official description above is the record.