# CVE-2024-26906: x86/mm: Disallow vsyscall page read for copy_from_kernel_nofault()

> A local attacker can trigger a kernel oops and system crash by using BPF programs to read from the vsyscall page.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 17 Apr 2024
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2024-26906, DEBIAN-CVE-2024-26906, GHSA-h4jh-5vqp-vw3p, UBUNTU-CVE-2024-26906

## What is CVE-2024-26906?

CVE-2024-26906 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 17 Apr 2024. 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:

x86/mm: Disallow vsyscall page read for copy_from_kernel_nofault()

When trying to use copy_from_kernel_nofault() to read vsyscall page
through a bpf program, the following oops was reported:

  BUG: unable to handle page fault for address: ffffffffff600000
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 3231067 P4D 3231067 PUD 3233067 PMD 3235067 PTE 0
  Oops: 0000 [#1] PREEMPT SMP PTI
  CPU: 1 PID: 20390 Comm: test_progs ...... 6.7.0+ #58
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) ......
  RIP: 0010:copy_from_kernel_nofault+0x6f/0x110
  ......
  Call Trace:
   <TASK>
   ? copy_from_kernel_nofault+0x6f/0x110
   bpf_probe_read_kernel+0x1d/0x50
   bpf_prog_2061065e56845f08_do_probe_read+0x51/0x8d
   trace_call_bpf+0xc5/0x1c0
   perf_call_bpf_enter.isra.0+0x69/0xb0
   perf_syscall_enter+0x13e/0x200
   syscall_trace_enter+0x188/0x1c0
   do_syscall_64+0xb5/0xe0
   entry_SYSCALL_64_after_hwframe+0x6e/0x76
   </TASK>
  ......
  ---[ end trace 0000000000000000 ]---

The oops is triggered when:

1) A bpf program uses bpf_probe_read_kernel() to read from the vsyscall
page and invokes copy_from_kernel_nofault() which in turn calls
__get_user_asm().

2) Because the vsyscall page address is not readable from kernel space,
a page fault exception is triggered accordingly.

3) handle_page_fault() considers the vsyscall page address as a user
space address instead of a kernel space address. This results in the
fix-up setup by bpf not being applied and a page_fault_oops() is invoked
due to SMAP.

Considering handle_page_fault() has already considered the vsyscall page
address as a userspace address, fix the problem by disallowing vsyscall
page read for copy_from_kernel_nofault().

## Which versions are affected by CVE-2024-26906?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2024-26906?

Apply the vendor's patch.

## Is CVE-2024-26906 being exploited?

There is no known exploitation of CVE-2024-26906 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-2024-26906 and fix it if it is affected.

What it is: CVE-2024-26906 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 17 Apr 2024. 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-2024-26906 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-2024-26906/ (Markdown: https://insights.sbomify.com/CVE-2024-26906/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-26906
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-26906
- OSV: https://osv.dev/vulnerability/CVE-2024-26906

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-26906/
Summaries are generated and may contain mistakes; the official description above is the record.