# CVE-2026-64190: net: team: fix NULL pointer dereference in team_xmit during mode change

> A race condition in the Linux kernel team driver allows a local attacker with CAP_NET_ADMIN to crash the system via a NULL pointer dereference.

- **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:** 20 Jul 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-92862, BELL-CVE-2026-64190, DEBIAN-CVE-2026-64190, GHSA-fg66-cp5r-9m26, ROOT-OS-DEBIAN-11-CVE-2026-64190, ROOT-OS-DEBIAN-12-CVE-2026-64190, ROOT-OS-UBUNTU-2204-CVE-2026-64190, UBUNTU-CVE-2026-64190

## What is CVE-2026-64190?

CVE-2026-64190 is a medium-severity vulnerability in Linux kernel, published on 20 Jul 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:

net: team: fix NULL pointer dereference in team_xmit during mode change

__team_change_mode() clears team->ops with memset() before restoring
safe dummy handlers via team_adjust_ops(). A concurrent team_xmit()
running under RCU on another CPU can read team->ops.transmit during
this window and call a NULL function pointer, crashing the kernel.

The race requires a mode change (CAP_NET_ADMIN) concurrent with
transmit on the team device.

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 Oops: 0010 [#1] SMP KASAN NOPTI
 RIP: 0010:0x0
 Call Trace:
  team_xmit (drivers/net/team/team_core.c:1853)
  dev_hard_start_xmit (net/core/dev.c:3904)
  __dev_queue_xmit (net/core/dev.c:4871)
  packet_sendmsg (net/packet/af_packet.c:3109)
  __sys_sendto (net/socket.c:2265)

The original code assumed that no ports means no traffic, so mode
changes could freely memset()/memcpy() the ops.  AF_PACKET with
forced carrier breaks that assumption.

Prevent the race instead of making it safe: replace memset()/memcpy()
with per-field updates that never touch transmit or receive.  Those
two handlers are managed solely by team_adjust_ops(), which already
installs dummies when tx_en_port_count == 0 (always true during mode
change since no ports are present).  WRITE_ONCE/READ_ONCE prevent
store/load tearing on the handler pointers.

synchronize_net() before exit_op() drains in-flight readers that may
still reference old mode state from before port removal switched the
handlers to dummies.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-64190?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64190?

Apply the vendor's patch.

## Is CVE-2026-64190 being exploited?

There is no known exploitation of CVE-2026-64190 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-2026-64190 and fix it if it is affected.

What it is: CVE-2026-64190 is a medium-severity vulnerability in Linux kernel, published on 20 Jul 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-2026-64190 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-2026-64190/ (Markdown: https://insights.sbomify.com/CVE-2026-64190/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64190
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64190
- OSV: https://osv.dev/vulnerability/CVE-2026-64190

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64190/
Summaries are generated and may contain mistakes; the official description above is the record.