medium CVSS 5.5 EPSS <0.1%

CVE-2021-47612·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: nfc: fix segfault in nfc_genl_dump_devices_done When kmalloc in nfc_genl_dump_devices() fails then nfc_genl_dump_devices_done() segfaults as below KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 0 PID: 25 Comm: kworker/0:1 Not tainted 5.16.0-rc4-01180-g2a987e65025e-dirty #5 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-6.fc35 04/01/2014 Workqueue: events netlink_sock_destruct_work RIP: 0010:klist_iter_exit+0x26/0x80 Call Trace: <TASK> class_dev_iter_exit+0x15/0x20 nfc_genl_dump_devices_done+0x3b/0x50 genl_lock_done+0x84/0xd0 netlink_sock_destruct+0x8f/0x270 __sk_destruct+0x64/0x3b0 sk_destruct+0xa8/0xd0 __sk_free+0x2e8/0x3d0 sk_free+0x51/0x90 netlink_sock_destruct_work+0x1c/0x20 process_one_work+0x411/0x710 worker_thread+0x6fd/0xa80

Severity
medium
Software
Kernel
Fixed in
5.15.10
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 7% 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.

Affected versions

From: 5.11

Until: 5.15.10

Fixed in: 5.15.10

How to fix this CVE

Update your Linux kernel to version 5.15.10 or later to resolve a null pointer dereference in the NFC generic netlink handler that can cause kernel crashes when memory allocation fails. This vulnerability affects kernel versions 5.11 through 5.15.9 and should be patched promptly to ensure system stability and availability.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Check your kernel version with: uname -r. Vulnerable versions are 5.11.x through 5.15.9.
  2. Verify NFC subsystem is enabled: grep -i nfc /boot/config-$(uname -r) | grep -E 'CONFIG_NFC=|CONFIG_NFC_NETLINK='
  3. Search system logs for NFC-related kernel panics or null pointer dereference errors: sudo grep -i 'nfc_genl_dump_devices\|null-ptr-deref' /var/log/kern.log /var/log/syslog 2>/dev/null
  4. After patching, confirm the updated kernel is loaded: uname -r should show version 5.15.10 or later, and reboot if necessary with: sudo reboot

FAQ

What is CVE-2021-47612?

CVE-2021-47612 is a null pointer dereference bug in the Linux kernel's NFC (Near Field Communication) netlink interface. When kernel memory allocation fails during NFC device enumeration, the cleanup routine crashes instead of gracefully handling the error, causing a kernel panic.

Is CVE-2021-47612 being actively exploited?

No, this vulnerability is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits are available. However, it can still cause denial of service through local system crashes.

What versions of Kernel are affected by CVE-2021-47612?

Linux kernel versions 5.11.0 through 5.15.9 are vulnerable. The fix was released in kernel version 5.15.10.

How do I check if my server is vulnerable to CVE-2021-47612?

Run: uname -r. If the output shows a version between 5.11 and 5.15.9 (inclusive), your system is vulnerable. Additionally, check if NFC is enabled with: grep CONFIG_NFC /boot/config-$(uname -r)

Does Defensia detect CVE-2021-47612?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2021-47612 will appear in your dashboard with remediation steps.

Related Kernel CVEs

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CVE-2026-53228CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ipv6: sit: reload inner IPv6 header after GSO offloads ipip6_tunnel_xmit() caches the inner IPv6 header pointer at function entry and continues using it after iptunnel_handle_offloads(). For GSO skbs, iptunnel_handle_offloads() calls skb_header_unclone(). When the skb header is cloned, skb_header_unclone() can call pskb_expand_head(), which may move the skb head. The pskb_expand_head() contract requires pointers into the skb header to be reloaded after the call. If the later skb_realloc_headroom() branch is not taken, SIT uses the stale iph6 pointer to read the inner hop limit and DS field. That can read from a freed skb head after the old head's remaining clone is released. Reload iph6 after the offload helper succeeds and before subsequent reads from the inner IPv6 header. Keep the existing reload after skb_realloc_headroom(), since that branch can also replace the skb.

References

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