high CVSS 7.8 EPSS <0.1%

CVE-2024-50257·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: netfilter: Fix use-after-free in get_info() ip6table_nat module unload has refcnt warning for UAF. call trace is: WARNING: CPU: 1 PID: 379 at kernel/module/main.c:853 module_put+0x6f/0x80 Modules linked in: ip6table_nat(-) CPU: 1 UID: 0 PID: 379 Comm: ip6tables Not tainted 6.12.0-rc4-00047-gc2ee9f594da8-dirty #205 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:module_put+0x6f/0x80 Call Trace: <TASK> get_info+0x128/0x180 do_ip6t_get_ctl+0x6a/0x430 nf_getsockopt+0x46/0x80 ipv6_getsockopt+0xb9/0x100 rawv6_getsockopt+0x42/0x190 do_sock_getsockopt+0xaa/0x180 __sys_getsockopt+0x70/0xc0 __x64_sys_getsockopt+0x20/0x30 do_syscall_64+0xa2/0x1a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Concurrent execution of module unload and get_info() trigered the warning. The root cause is as follows: cpu0 cpu1 module_exit //mod->state = MODULE_STATE_GOING ip6table_nat_exit xt_unregister_template kfree(t) //removed from templ_list getinfo() t = xt_find_table_lock list_for_each_entry(tmpl, &xt_templates[af]...) if (strcmp(tmpl->name, name)) continue; //table not found try_module_get list_for_each_entry(t, &xt_net->tables[af]...) return t; //not get refcnt module_put(t->me) //uaf unregister_pernet_subsys //remove table from xt_net list While xt_table module was going away and has been removed from xt_templates list, we couldnt get refcnt of xt_table->me. Check module in xt_net->tables list re-traversal to fix it.

Severity
high
Software
Kernel
Fixed in
6.11.7
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 <0.1% — higher than 11% 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-2024-50257 scores 7.8 on CVSS, so a successful attack would be serious — but at <0.1%, 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: 6.7

Until: 6.11.7

Fixed in: 6.11.7

How to fix this CVE

Update your Linux kernel to version 6.11.7 or later to resolve a use-after-free vulnerability in the netfilter module's get_info() function. This flaw occurs when the ip6table_nat module is unloaded concurrently with netfilter socket operations, allowing a local attacker with privileges to trigger memory corruption. Apply the kernel update immediately through your distribution's package manager.

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` and compare against the affected range (6.7 to 6.11.7). If your version is between these numbers, your system is vulnerable.
  2. Step 2: Verify if netfilter ip6table_nat module is loaded by running `lsmod | grep ip6table_nat`. If present, the vulnerable code path is available.
  3. Step 3: Search system logs for module reference count warnings with `grep -i 'module_put\|refcnt warning' /var/log/kern.log /var/log/syslog`. Look for patterns matching 'WARNING.*module_put' or 'ip6table_nat' errors.
  4. Step 4: After applying patches, confirm the new kernel is in use with `uname -r` and verify it shows version 6.11.7 or later, then reboot if needed.

FAQ

What is CVE-2024-50257?

CVE-2024-50257 is a use-after-free vulnerability in the Linux kernel's netfilter subsystem that occurs when the ip6table_nat module is unloaded while concurrent socket operations are accessing netfilter configuration through get_info(). A local privileged attacker can exploit this race condition to corrupt kernel memory.

Is CVE-2024-50257 being actively exploited?

No, CVE-2024-50257 is not listed on CISA's Known Exploited Vulnerabilities catalog and has no public exploit code available. However, it is a high-severity local privilege escalation vector that warrants prompt patching.

What versions of Kernel are affected by CVE-2024-50257?

Linux kernel versions 6.7 through 6.11.6 are vulnerable. Kernel version 6.11.7 and all later versions contain the fix.

How do I check if my server is vulnerable to CVE-2024-50257?

Run `uname -r` to get your kernel version. If it falls between 6.7 and 6.11.6 (inclusive), and `lsmod | grep ip6table_nat` shows the module is loaded, your system is vulnerable.

Does Defensia detect CVE-2024-50257?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2024-50257 will appear in your dashboard with remediation steps.

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References

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