# CVE-2024-50085: mptcp: pm: fix UaF read in mptcp_pm_nl_rm_addr_or_subflow

> A use-after-free vulnerability in the Linux kernel's MPTCP path manager allows local attackers to cause a system crash or potentially execute arbitrary code.

- **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:** 29 Oct 2024
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-51936, BELL-CVE-2024-50085, DEBIAN-CVE-2024-50085, GHSA-777g-cfq7-cgv7, UBUNTU-CVE-2024-50085

## What is CVE-2024-50085?

CVE-2024-50085 is a critical use after free vulnerability in Linux kernel, published on 29 Oct 2024. 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:

mptcp: pm: fix UaF read in mptcp_pm_nl_rm_addr_or_subflow

Syzkaller reported this splat:

  ==================================================================
  BUG: KASAN: slab-use-after-free in mptcp_pm_nl_rm_addr_or_subflow+0xb44/0xcc0 net/mptcp/pm_netlink.c:881
  Read of size 4 at addr ffff8880569ac858 by task syz.1.2799/14662

  CPU: 0 UID: 0 PID: 14662 Comm: syz.1.2799 Not tainted 6.12.0-rc2-syzkaller-00307-g36c254515dc6 #0
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
  Call Trace:
   <TASK>
   __dump_stack lib/dump_stack.c:94 [inline]
   dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
   print_address_description mm/kasan/report.c:377 [inline]
   print_report+0xc3/0x620 mm/kasan/report.c:488
   kasan_report+0xd9/0x110 mm/kasan/report.c:601
   mptcp_pm_nl_rm_addr_or_subflow+0xb44/0xcc0 net/mptcp/pm_netlink.c:881
   mptcp_pm_nl_rm_subflow_received net/mptcp/pm_netlink.c:914 [inline]
   mptcp_nl_remove_id_zero_address+0x305/0x4a0 net/mptcp/pm_netlink.c:1572
   mptcp_pm_nl_del_addr_doit+0x5c9/0x770 net/mptcp/pm_netlink.c:1603
   genl_family_rcv_msg_doit+0x202/0x2f0 net/netlink/genetlink.c:1115
   genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
   genl_rcv_msg+0x565/0x800 net/netlink/genetlink.c:1210
   netlink_rcv_skb+0x165/0x410 net/netlink/af_netlink.c:2551
   genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
   netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline]
   netlink_unicast+0x53c/0x7f0 net/netlink/af_netlink.c:1357
   netlink_sendmsg+0x8b8/0xd70 net/netlink/af_netlink.c:1901
   sock_sendmsg_nosec net/socket.c:729 [inline]
   __sock_sendmsg net/socket.c:744 [inline]
   ____sys_sendmsg+0x9ae/0xb40 net/socket.c:2607
   ___sys_sendmsg+0x135/0x1e0 net/socket.c:2661
   __sys_sendmsg+0x117/0x1f0 net/socket.c:2690
   do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
   __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
   do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
   entry_SYSENTER_compat_after_hwframe+0x84/0x8e
  RIP: 0023:0xf7fe4579
  Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
  RSP: 002b:00000000f574556c EFLAGS: 00000296 ORIG_RAX: 0000000000000172
  RAX: ffffffffffffffda RBX: 000000000000000b RCX: 0000000020000140
  RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
  RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
  R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
   </TASK>

  Allocated by task 5387:
   kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
   kasan_save_track+0x14/0x30 mm/kasan/common.c:68
   poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
   __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
   kmalloc_noprof include/linux/slab.h:878 [inline]
   kzalloc_noprof include/linux/slab.h:1014 [inline]
   subflow_create_ctx+0x87/0x2a0 net/mptcp/subflow.c:1803
   subflow_ulp_init+0xc3/0x4d0 net/mptcp/subflow.c:1956
   __tcp_set_ulp net/ipv4/tcp_ulp.c:146 [inline]
   tcp_set_ulp+0x326/0x7f0 net/ipv4/tcp_ulp.c:167
   mptcp_subflow_create_socket+0x4ae/0x10a0 net/mptcp/subflow.c:1764
   __mptcp_subflow_connect+0x3cc/0x1490 net/mptcp/subflow.c:1592
   mptcp_pm_create_subflow_or_signal_addr+0xbda/0x23a0 net/mptcp/pm_netlink.c:642
   mptcp_pm_nl_fully_established net/mptcp/pm_netlink.c:650 [inline]
   mptcp_pm_nl_work+0x3a1/0x4f0 net/mptcp/pm_netlink.c:943
   mptcp_worker+0x15a/0x1240 net/mptcp/protocol.c:2777
   process_one_work+0x958/0x1b30 kernel/workqueue.c:3229
   process_scheduled_works kernel/workqueue.c:3310 [inline]
   worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
   kthread+0x2c1/0x3a0 kernel/kthread.c:389
   ret_from_fork+0x45/0x80 arch/x86/ke
---truncated---

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2024-50085?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-50085?

Apply the vendor's patch.

## Is CVE-2024-50085 being exploited?

There is no known exploitation of CVE-2024-50085 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-2024-50085 and fix it if it is affected.

What it is: CVE-2024-50085 is a critical use after free vulnerability in Linux kernel, published on 29 Oct 2024. 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-2024-50085 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-2024-50085/ (Markdown: https://insights.sbomify.com/CVE-2024-50085/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-50085
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-50085
- OSV: https://osv.dev/vulnerability/CVE-2024-50085

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-50085/
Summaries are generated and may contain mistakes; the official description above is the record.