How severe is CVE-2021-47399?

CVE-2021-47399 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-47399 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-47399?

CVE-2021-47399 primarily affects Linux Linux Kernel. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-47399?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2021-47399 have an EU (EUVD) identifier?

Yes. CVE-2021-47399 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-34404.

When was CVE-2021-47399 published?

CVE-2021-47399 was published on 2024-05-21 and last updated on 2026-06-17.

CVE-2021-47399

CVE-2021-47399 is a medium-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-476.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2021-34404
Weakness: CWE-476
Affected product: Linux Linux Kernel
Published: 2024-05-21
Last modified: 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: ixgbe: Fix NULL pointer dereference in ixgbe_xdp_setup The ixgbe driver currently generates a NULL pointer dereference with some machine (online cpus < 63). This is due to the fact that the maximum value of num_xdp_queues is nr_cpu_ids. Code is in "ixgbe_set_rss_queues"". Here's how the problem repeats itself: Some machine (online cpus < 63), And user set num_queues to 63 through ethtool. Code is in the "ixgbe_set_channels", adapter->ring_feature[RING_F_FDIR].limit = count; It becomes 63. When user use xdp, "ixgbe_set_rss_queues" will set queues num. adapter->num_rx_queues = rss_i; adapter->num_tx_queues = rss_i; adapter->num_xdp_queues = ixgbe_xdp_queues(adapter); And rss_i's value is from f = &adapter->ring_feature[RING_F_FDIR]; rss_i = f->indices = f->limit; So "num_rx_queues" > "num_xdp_queues", when run to "ixgbe_xdp_setup", for (i = 0; i < adapter->num_rx_queues; i++) if (adapter->xdp_ring[i]->xsk_umem) It leads to panic. Call trace: [exception RIP: ixgbe_xdp+368] RIP: ffffffffc02a76a0 RSP: ffff9fe16202f8d0 RFLAGS: 00010297 RAX: 0000000000000000 RBX: 0000000000000020 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 000000000000001c RDI: ffffffffa94ead90 RBP: ffff92f8f24c0c18 R8: 0000000000000000 R9: 0000000000000000 R10: ffff9fe16202f830 R11: 0000000000000000 R12: ffff92f8f24c0000 R13: ffff9fe16202fc01 R14: 000000000000000a R15: ffffffffc02a7530 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 7 [ffff9fe16202f8f0] dev_xdp_install at ffffffffa89fbbcc 8 [ffff9fe16202f920] dev_change_xdp_fd at ffffffffa8a08808 9 [ffff9fe16202f960] do_setlink at ffffffffa8a20235 10 [ffff9fe16202fa88] rtnl_setlink at ffffffffa8a20384 11 [ffff9fe16202fc78] rtnetlink_rcv_msg at ffffffffa8a1a8dd 12 [ffff9fe16202fcf0] netlink_rcv_skb at ffffffffa8a717eb 13 [ffff9fe16202fd40] netlink_unicast at ffffffffa8a70f88 14 [ffff9fe16202fd80] netlink_sendmsg at ffffffffa8a71319 15 [ffff9fe16202fdf0] sock_sendmsg at ffffffffa89df290 16 [ffff9fe16202fe08] __sys_sendto at ffffffffa89e19c8 17 [ffff9fe16202ff30] __x64_sys_sendto at ffffffffa89e1a64 18 [ffff9fe16202ff38] do_syscall_64 at ffffffffa84042b9 19 [ffff9fe16202ff50] entry_SYSCALL_64_after_hwframe at ffffffffa8c0008c So I fix ixgbe_max_channels so that it will not allow a setting of queues to be higher than the num_online_cpus(). And when run to ixgbe_xdp_setup, take the smaller value of num_rx_queues and num_xdp_queues.

Frequently asked questions

What is CVE-2021-47399?: In the Linux kernel, the following vulnerability has been resolved: ixgbe: Fix NULL pointer dereference in ixgbe_xdp_setup The ixgbe driver currently generates a NULL pointer dereference with some machine (online cpus < 63). This is due to the fact that the maximum value of num_xdp_queues is nr_cpu_ids. Code is in "ixgbe_set_rss_queues"". Here's how the problem repeats itself: Some machine (online cpus < 63), And user set num_queues to 63 through ethtool. Code is in the "ixgbe_set_channels", adapter->ring_feature[RING_F_FDIR].limit = count; It becomes 63. When user use xdp, "ixgbe_set_rss_queues" will set queues num. adapter->num_rx_queues = rss_i; adapter->num_tx_queues = rss_i; adapter->num_xdp_queues = ixgbe_xdp_queues(adapter); And rss_i's value is from f = &adapter->ring_feature[RING_F_FDIR]; rss_i = f->indices = f->limit; So "num_rx_queues" > "num_xdp_queues", when run to "ixgbe_xdp_setup", for (i = 0; i < adapter->num_rx_queues; i++) if (adapter->xdp_ring[i]->xsk_umem) It leads to panic. Call trace: [exception RIP: ixgbe_xdp+368] RIP: ffffffffc02a76a0 RSP: ffff9fe16202f8d0 RFLAGS: 00010297 RAX: 0000000000000000 RBX: 0000000000000020 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 000000000000001c RDI: ffffffffa94ead90 RBP: ffff92f8f24c0c18 R8: 0000000000000000 R9: 0000000000000000 R10: ffff9fe16202f830 R11: 0000000000000000 R12: ffff92f8f24c0000 R13: ffff9fe16202fc01 R14: 000000000000000a R15: ffffffffc02a7530 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 7 [ffff9fe16202f8f0] dev_xdp_install at ffffffffa89fbbcc 8 [ffff9fe16202f920] dev_change_xdp_fd at ffffffffa8a08808 9 [ffff9fe16202f960] do_setlink at ffffffffa8a20235 10 [ffff9fe16202fa88] rtnl_setlink at ffffffffa8a20384 11 [ffff9fe16202fc78] rtnetlink_rcv_msg at ffffffffa8a1a8dd 12 [ffff9fe16202fcf0] netlink_rcv_skb at ffffffffa8a717eb 13 [ffff9fe16202fd40] netlink_unicast at ffffffffa8a70f88 14 [ffff9fe16202fd80] netlink_sendmsg at ffffffffa8a71319 15 [ffff9fe16202fdf0] sock_sendmsg at ffffffffa89df290 16 [ffff9fe16202fe08] __sys_sendto at ffffffffa89e19c8 17 [ffff9fe16202ff30] __x64_sys_sendto at ffffffffa89e1a64 18 [ffff9fe16202ff38] do_syscall_64 at ffffffffa84042b9 19 [ffff9fe16202ff50] entry_SYSCALL_64_after_hwframe at ffffffffa8c0008c So I fix ixgbe_max_channels so that it will not allow a setting of queues to be higher than the num_online_cpus(). And when run to ixgbe_xdp_setup, take the smaller value of num_rx_queues and num_xdp_queues.
How severe is CVE-2021-47399?: CVE-2021-47399 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-47399 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-47399?: CVE-2021-47399 primarily affects Linux Linux Kernel. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-47399?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2021-47399 have an EU (EUVD) identifier?: Yes. CVE-2021-47399 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-34404.
When was CVE-2021-47399 published?: CVE-2021-47399 was published on 2024-05-21 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:*

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