# CVE-2026-97937: ftrace: fork: Initialize function graph state before copy_exec_state()

> A use-after-free in the Linux kernel ftrace subsystem allows local attackers to execute arbitrary code or escalate privileges via a race condition during fork.

- **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:** 25 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-97937, GHSA-79j5-369g-hx4m, UBUNTU-CVE-2026-97937

## What is CVE-2026-97937?

CVE-2026-97937 is a high-severity use after free vulnerability in Linux, published on 25 Sep 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:

ftrace: fork: Initialize function graph state before copy_exec_state()

dup_task_struct() copies the parent's task_struct, including ret_stack.
ftrace_graph_init_task() clears the copied function graph state, but it
currently runs after copy_exec_state().

For non-CLONE_VM forks, copy_exec_state() allocates a new task_exec_state.
If that allocation fails, copy_process() reaches bad_fork_free and
free_task() calls ftrace_graph_exit_task(). Since the child still carries
the parent's ret_stack pointer, the unwind frees the parent's active
function graph return stack. The parent subsequently accesses freed memory
from function_graph_enter_regs().

KASAN reports:

[   22.190920] ==================================================================
[   22.195899] BUG: KASAN: slab-use-after-free in function_graph_enter_regs+0xa76/0xb90
[   22.200747] Write of size 8 at addr ff110000054dc0a8 by task repro/1
[   22.205134]
[   22.210770] CPU: 0 UID: 0 PID: 1 Comm: repro Not tainted 7.2.0-07732-g9328b3b03bdc-dirty #3 PREEMPT(lazy)
[   22.212576] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[   22.213750] Call Trace:
[   22.215271]  <TASK>
[   22.216242]  ? ftrace_stub_direct_tramp+0x10/0x10
[   22.217774]  dump_stack_lvl+0x4e/0x70
[   22.220531]  print_report+0x157/0x4b4
[   22.223202]  ? fixup_red_left+0x9/0x30
[   22.224407]  ? complete_report_info+0x83/0x110
[   22.226679]  ? function_graph_enter_regs+0xa76/0xb90
[   22.228084]  kasan_report+0xce/0x100
[   22.230109]  ? function_graph_enter_regs+0xa76/0xb90
[   22.232860]  ? stack_trace_save+0x4/0xd0
[   22.234156]  function_graph_enter_regs+0xa76/0xb90
[   22.236090]  ? kasan_save_stack+0x30/0x50
[   22.237752]  ? __pfx_function_graph_enter_regs+0x10/0x10
[   22.238694]  ? ring_buffer_lock_reserve+0x345/0xf80
[   22.239628]  ? stack_trace_save+0x4/0xd0
[   22.242121]  ? stack_trace_save+0x4/0xd0
[   22.243588]  ftrace_graph_func+0xda/0x160
[   22.245362]  ? ftrace_stub_direct_tramp+0x10/0x10
[   22.246520]  0xffffffffa0000095
[   22.250528]  ? stack_trace_save+0x9/0xd0
[   22.251757]  ? ring_buffer_unlock_commit+0x11d/0x5c0
[   22.253152]  stack_trace_save+0x9/0xd0
[   22.254264]  kasan_save_stack+0x30/0x50
[   22.273631]  kasan_save_track+0x14/0x30
[   22.276763]  kasan_save_free_info+0x3b/0x70
[   22.278296]  __kasan_slab_free+0x43/0x70
[   22.280157]  kmem_cache_free+0xbf/0x3b0
[   22.282963]  ? ftrace_stub_direct_tramp+0x10/0x10
[   22.284001]  free_task+0xa2/0x160
[   22.285699]  ? ftrace_stub_direct_tramp+0x10/0x10
[   22.286752]  copy_process+0x2aae/0x7bc0

Initialize the child function graph state immediately after
dup_task_struct(), before the first fallible operation.

## Which versions are affected by CVE-2026-97937?


## How do I fix CVE-2026-97937?

Apply the vendor's patch.

## Is CVE-2026-97937 being exploited?

There is no known exploitation of CVE-2026-97937 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97937 and fix it if it is affected.

What it is: CVE-2026-97937 is a high-severity use after free vulnerability in Linux, published on 25 Sep 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-2026-97937 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-2026-97937/ (Markdown: https://insights.sbomify.com/CVE-2026-97937/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97937
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97937
- OSV: https://osv.dev/vulnerability/CVE-2026-97937

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97937/
Summaries are generated and may contain mistakes; the official description above is the record.