# CVE-2026-64141: ksmbd: fix null pointer dereference in compare_guid_key()

> A null pointer dereference in the Linux kernel's ksmbd module allows remote attackers to cause a system crash via crafted SMB2 requests.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 Jul 2026
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2026-64141, DEBIAN-CVE-2026-64141, GHSA-5c3g-3v2r-672g, UBUNTU-CVE-2026-64141

## What is CVE-2026-64141?

CVE-2026-64141 is a high-severity vulnerability in Linux kernel, published on 19 Jul 2026. 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: fix null pointer dereference in compare_guid_key()

session_fd_check() walks the per-inode m_op_list during durable-handle
session teardown and sets op->conn = NULL for every opinfo whose conn
matched the closing session's connection. The matching opinfo, however,
stays linked in its per-ClientGuid lease_table_list entry's lb->lease_list
because destroy_lease_table() only runs on full TCP-connection teardown,
not on SESSION_LOGOFF.

If the same TCP connection then negotiates a fresh session with the
same ClientGuid (ClientGuid is bound to NEGOTIATE, not the session, and
is unchanged across LOGOFF + SETUP) and issues a SMB2 CREATE with a
lease context on a different inode, find_same_lease_key() walks
lb->lease_list, reaches the stale opinfo, and calls compare_guid_key(),
which unconditionally dereferences opinfo->conn->ClientGUID. The conn
pointer is NULL and the kernel panics.

Reproducer requires only a successful SMB2 SESSION_SETUP and a share
configured with 'durable handles = yes'. KASAN report on mainline
70390501d194:

  general protection fault, probably for non-canonical address
  0xdffffc0000000069: 0000 [#1] SMP KASAN PTI
  KASAN: null-ptr-deref in range [0x0000000000000348-0x000000000000034f]
  Workqueue: ksmbd-io handle_ksmbd_work
  RIP: 0010:bcmp+0x5b/0x230
  Call Trace:
   compare_guid_key+0x4b/0xd0
   find_same_lease_key+0x324/0x690
   smb2_open+0x6aea/0x8e60
   handle_ksmbd_work+0x796/0xee0
   ...

Faulting address 0x348 is the offset of ClientGUID within struct
ksmbd_conn, confirming opinfo->conn was NULL.

Read opinfo->conn once and bail out if it has been cleared by a
concurrent session_fd_check(). A half-detached opinfo cannot be the
owner of an active lease, so returning 0 is the correct match result.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-64141?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64141?

Apply the vendor's patch.

## Is CVE-2026-64141 being exploited?

There is no known exploitation of CVE-2026-64141 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64141 and fix it if it is affected.

What it is: CVE-2026-64141 is a high-severity vulnerability in Linux kernel, published on 19 Jul 2026. 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-2026-64141 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-64141/ (Markdown: https://insights.sbomify.com/CVE-2026-64141/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64141
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64141
- OSV: https://osv.dev/vulnerability/CVE-2026-64141

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64141/
Summaries are generated and may contain mistakes; the official description above is the record.