# CVE-2025-38574: pptp: ensure minimal skb length in pptp_xmit()

> A missing length check in the Linux kernel PPTP driver allows attackers to read uninitialized memory, potentially disclosing sensitive kernel data.

- **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Aug 2025
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-66476, AZL-73857, BELL-CVE-2025-38574, DEBIAN-CVE-2025-38574, GHSA-39q5-4vqc-9p73, ROOT-OS-DEBIAN-11-CVE-2025-38574, ROOT-OS-DEBIAN-12-CVE-2025-38574, ROOT-OS-DEBIAN-13-CVE-2025-38574, ROOT-OS-UBUNTU-2204-CVE-2025-38574, ROOT-OS-UBUNTU-2404-CVE-2025-38574, UBUNTU-CVE-2025-38574

## What is CVE-2025-38574?

CVE-2025-38574 is a high-severity vulnerability in Debian Debian Linux, published on 19 Aug 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

pptp: ensure minimal skb length in pptp_xmit()

Commit aabc6596ffb3 ("net: ppp: Add bound checking for skb data
on ppp_sync_txmung") fixed ppp_sync_txmunge()

We need a similar fix in pptp_xmit(), otherwise we might
read uninit data as reported by syzbot.

BUG: KMSAN: uninit-value in pptp_xmit+0xc34/0x2720 drivers/net/ppp/pptp.c:193
  pptp_xmit+0xc34/0x2720 drivers/net/ppp/pptp.c:193
  ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2290 [inline]
  ppp_input+0x1d6/0xe60 drivers/net/ppp/ppp_generic.c:2314
  pppoe_rcv_core+0x1e8/0x760 drivers/net/ppp/pppoe.c:379
  sk_backlog_rcv+0x142/0x420 include/net/sock.h:1148
  __release_sock+0x1d3/0x330 net/core/sock.c:3213
  release_sock+0x6b/0x270 net/core/sock.c:3767
  pppoe_sendmsg+0x15d/0xcb0 drivers/net/ppp/pppoe.c:904
  sock_sendmsg_nosec net/socket.c:712 [inline]
  __sock_sendmsg+0x330/0x3d0 net/socket.c:727
  ____sys_sendmsg+0x893/0xd80 net/socket.c:2566
  ___sys_sendmsg+0x271/0x3b0 net/socket.c:2620
  __sys_sendmmsg+0x2d9/0x7c0 net/socket.c:2709

Weakness: CWE-908 (Use of Uninitialized Resource)

## Which versions are affected by CVE-2025-38574?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-38574?

Apply the vendor's patch.

## Is CVE-2025-38574 being exploited?

There is no known exploitation of CVE-2025-38574 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [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-2025-38574 and fix it if it is affected.

What it is: CVE-2025-38574 is a high-severity vulnerability in Debian Debian Linux, published on 19 Aug 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-38574 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-2025-38574/ (Markdown: https://insights.sbomify.com/CVE-2025-38574/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38574
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38574
- OSV: https://osv.dev/vulnerability/CVE-2025-38574

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38574/
Summaries are generated and may contain mistakes; the official description above is the record.