# CVE-2025-68263: ksmbd: ipc: fix use-after-free in ipc_msg_send_request

> A race condition in the Linux kernel's ksmbd module allows a use-after-free, potentially enabling local attackers to execute code or escalate privileges.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 16 Dec 2025
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2025-68263, DEBIAN-CVE-2025-68263, GHSA-j5fg-gwpm-pjw5, ROOT-OS-DEBIAN-12-CVE-2025-68263, ROOT-OS-DEBIAN-13-CVE-2025-68263, ROOT-OS-UBUNTU-2204-CVE-2025-68263, ROOT-OS-UBUNTU-2404-CVE-2025-68263, UBUNTU-CVE-2025-68263

## What is CVE-2025-68263?

CVE-2025-68263 is a critical use after free vulnerability in Linux, published on 16 Dec 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:

ksmbd: ipc: fix use-after-free in ipc_msg_send_request

ipc_msg_send_request() waits for a generic netlink reply using an
ipc_msg_table_entry on the stack. The generic netlink handler
(handle_generic_event()/handle_response()) fills entry->response under
ipc_msg_table_lock, but ipc_msg_send_request() used to validate and free
entry->response without holding the same lock.

Under high concurrency this allows a race where handle_response() is
copying data into entry->response while ipc_msg_send_request() has just
freed it, leading to a slab-use-after-free reported by KASAN in
handle_generic_event():

  BUG: KASAN: slab-use-after-free in handle_generic_event+0x3c4/0x5f0 [ksmbd]
  Write of size 12 at addr ffff888198ee6e20 by task pool/109349
  ...
  Freed by task:
    kvfree
    ipc_msg_send_request [ksmbd]
    ksmbd_rpc_open -> ksmbd_session_rpc_open [ksmbd]

Fix by:
- Taking ipc_msg_table_lock in ipc_msg_send_request() while validating
  entry->response, freeing it when invalid, and removing the entry from
  ipc_msg_table.
- Returning the final entry->response pointer to the caller only after
  the hash entry is removed under the lock.
- Returning NULL in the error path, preserving the original API
  semantics.

This makes all accesses to entry->response consistent with
handle_response(), which already updates and fills the response buffer
under ipc_msg_table_lock, and closes the race that allowed the UAF.

## Which versions are affected by CVE-2025-68263?


## How do I fix CVE-2025-68263?

Apply the vendor's patch.

## Is CVE-2025-68263 being exploited?

There is no known exploitation of CVE-2025-68263 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68263 and fix it if it is affected.

What it is: CVE-2025-68263 is a critical use after free vulnerability in Linux, published on 16 Dec 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-2025-68263 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-2025-68263/ (Markdown: https://insights.sbomify.com/CVE-2025-68263/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68263
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68263
- OSV: https://osv.dev/vulnerability/CVE-2025-68263

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68263/
Summaries are generated and may contain mistakes; the official description above is the record.