# CVE-2026-43016: bpf: sockmap: Fix use-after-free of sk->sk_socket in sk_psock_verdict_data_ready().

> A use-after-free vulnerability in the Linux kernel's BPF sockmap allows local attackers to potentially execute code or escalate privileges via AF_UNIX sockets.

- **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:** 1 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-43016, DEBIAN-CVE-2026-43016, GHSA-52mq-7c45-jwp5, ROOT-OS-DEBIAN-12-CVE-2026-43016, ROOT-OS-UBUNTU-2204-CVE-2026-43016, ROOT-OS-UBUNTU-2404-CVE-2026-43016, UBUNTU-CVE-2026-43016

## What is CVE-2026-43016?

CVE-2026-43016 is a high-severity use after free vulnerability in Linux kernel, published on 1 May 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:

bpf: sockmap: Fix use-after-free of sk->sk_socket in sk_psock_verdict_data_ready().

syzbot reported use-after-free of AF_UNIX socket's sk->sk_socket
in sk_psock_verdict_data_ready(). [0]

In unix_stream_sendmsg(), the peer socket's ->sk_data_ready() is
called after dropping its unix_state_lock().

Although the sender socket holds the peer's refcount, it does not
prevent the peer's sock_orphan(), and the peer's sk_socket might
be freed after one RCU grace period.

Let's fetch the peer's sk->sk_socket and sk->sk_socket->ops under
RCU in sk_psock_verdict_data_ready().

[0]:
BUG: KASAN: slab-use-after-free in sk_psock_verdict_data_ready+0xec/0x590 net/core/skmsg.c:1278
Read of size 8 at addr ffff8880594da860 by task syz.4.1842/11013

CPU: 1 UID: 0 PID: 11013 Comm: syz.4.1842 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 sk_psock_verdict_data_ready+0xec/0x590 net/core/skmsg.c:1278
 unix_stream_sendmsg+0x8a3/0xe80 net/unix/af_unix.c:2482
 sock_sendmsg_nosec net/socket.c:721 [inline]
 __sock_sendmsg net/socket.c:736 [inline]
 ____sys_sendmsg+0x972/0x9f0 net/socket.c:2585
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2639
 __sys_sendmsg net/socket.c:2671 [inline]
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2674
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7facf899c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007facf9827028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007facf8c15fa0 RCX: 00007facf899c819
RDX: 0000000000000000 RSI: 0000200000000500 RDI: 0000000000000004
RBP: 00007facf8a32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007facf8c16038 R14: 00007facf8c15fa0 R15: 00007ffd41b01c78
 </TASK>

Allocated by task 11013:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4538 [inline]
 slab_alloc_node mm/slub.c:4866 [inline]
 kmem_cache_alloc_lru_noprof+0x2b8/0x640 mm/slub.c:4885
 sock_alloc_inode+0x28/0xc0 net/socket.c:316
 alloc_inode+0x6a/0x1b0 fs/inode.c:347
 new_inode_pseudo include/linux/fs.h:3003 [inline]
 sock_alloc net/socket.c:631 [inline]
 __sock_create+0x12d/0x9d0 net/socket.c:1562
 sock_create net/socket.c:1656 [inline]
 __sys_socketpair+0x1c4/0x560 net/socket.c:1803
 __do_sys_socketpair net/socket.c:1856 [inline]
 __se_sys_socketpair net/socket.c:1853 [inline]
 __x64_sys_socketpair+0x9b/0xb0 net/socket.c:1853
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 15:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2685 [inline]
 slab_free mm/slub.c:6165 [inline]
 kmem_cache_free+0x187/0x630 mm/slub.c:6295
 rcu_do_batch kernel/rcu/tree.c:
---truncated---

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-43016?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43016?

Apply the vendor's patch.

## Is CVE-2026-43016 being exploited?

There is no known exploitation of CVE-2026-43016 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-2026-43016 and fix it if it is affected.

What it is: CVE-2026-43016 is a high-severity use after free vulnerability in Linux kernel, published on 1 May 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-2026-43016 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-2026-43016/ (Markdown: https://insights.sbomify.com/CVE-2026-43016/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43016
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43016
- OSV: https://osv.dev/vulnerability/CVE-2026-43016

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43016/
Summaries are generated and may contain mistakes; the official description above is the record.