high CVSS 7.8 EPSS 0.23%

CVE-2024-50155·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: netdevsim: use cond_resched() in nsim_dev_trap_report_work() I am still seeing many syzbot reports hinting that syzbot might fool nsim_dev_trap_report_work() with hundreds of ports [1] Lets use cond_resched(), and system_unbound_wq instead of implicit system_wq. [1] INFO: task syz-executor:20633 blocked for more than 143 seconds. Not tainted 6.12.0-rc2-syzkaller-00205-g1d227fcc7222 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor state:D stack:25856 pid:20633 tgid:20633 ppid:1 flags:0x00004006 ... NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 16760 Comm: kworker/1:0 Not tainted 6.12.0-rc2-syzkaller-00205-g1d227fcc7222 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: events nsim_dev_trap_report_work RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:210 Code: 89 fb e8 23 00 00 00 48 8b 3d 04 fb 9c 0c 48 89 de 5b e9 c3 c7 5d 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 8b 04 24 65 48 8b 0c 25 c0 d7 03 00 65 8b 15 60 f0 RSP: 0018:ffffc90000a187e8 EFLAGS: 00000246 RAX: 0000000000000100 RBX: ffffc90000a188e0 RCX: ffff888027d3bc00 RDX: ffff888027d3bc00 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88804a2e6000 R08: ffffffff8a4bc495 R09: ffffffff89da3577 R10: 0000000000000004 R11: ffffffff8a4bc2b0 R12: dffffc0000000000 R13: ffff88806573b503 R14: dffffc0000000000 R15: ffff8880663cca00 FS: 0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc90a747f98 CR3: 000000000e734000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 000000000000002b DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: <NMI> </NMI> <TASK> __local_bh_enable_ip+0x1bb/0x200 kernel/softirq.c:382 spin_unlock_bh include/linux/spinlock.h:396 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:820 [inline] nsim_dev_trap_report_work+0x75d/0xaa0 drivers/net/netdevsim/dev.c:850 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK>

Severity
high
Software
Kernel
Fixed in
6.11.6
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at 0.23% — higher than 14% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2024-50155 scores 7.8 on CVSS, so a successful attack would be serious — but at 0.23%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

From: 6.8

Until: 6.11.6

Fixed in: 6.11.6

How to fix this CVE

Update your Linux kernel to version 6.11.6 or later to patch the netdevsim work queue scheduling vulnerability. This fix improves CPU scheduling fairness by adding cooperative rescheduling points in trap report processing, preventing the kernel from becoming unresponsive when handling large numbers of simulated network device ports.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your kernel version with `uname -r` — compare against affected versions 6.8 to 6.11.5
  2. Step 2: Verify netdevsim is loaded with `lsmod | grep netdevsim` — if present, the vulnerable code path may be active
  3. Step 3: Check dmesg for hung task warnings: `dmesg | grep -i 'hung_task\|nsim_dev_trap_report'` — these indicate the scheduling issue
  4. Step 4: After patching, confirm with `uname -r` that you are running 6.11.6 or later, then reload netdevsim with `sudo modprobe -r netdevsim && sudo modprobe netdevsim`

FAQ

What is CVE-2024-50155?

This vulnerability exists in the Linux kernel's netdevsim module, where the trap report work function can starve the CPU scheduler when handling many simulated network ports, causing the system to appear hung. The fix adds rescheduling checkpoints to allow other tasks to run.

Is CVE-2024-50155 being actively exploited?

No, this is not listed in CISA's Known Exploited Vulnerabilities catalog and no public exploits are available. However, it can be triggered by test tools or fuzzing frameworks like syzbot.

What versions of Kernel are affected by CVE-2024-50155?

Kernel versions 6.8 through 6.11.5 are vulnerable. The fix is available in kernel 6.11.6 and later.

How do I check if my server is vulnerable to CVE-2024-50155?

Run `uname -r` and verify your kernel version is between 6.8 and 6.11.5. If you're running 6.11.6 or later, or versions before 6.8, you are not affected.

Does Defensia detect CVE-2024-50155?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2024-50155 will appear in your dashboard with remediation steps.

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References

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