high CVSS 7.8

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
2024-11-09

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.

Related Kernel CVEs

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References

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