CVE-2021-47397: sctp: break out if skb_header_pointer returns NULL in sctp_rcv_ootb

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-05-21 · updated 2026-08-04
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: sctp: break out if skb_header_pointer returns NULL in sctp_rcv_ootb We should always check if skb_header_pointer's return is NULL before using it, otherwise it may cause null-ptr-deref, as syzbot reported: KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:sctp_rcv_ootb net/sctp/input.c:705 [inline] RIP: 0010:sctp_rcv+0x1d84/0x3220 net/sctp/input.c:196 Call Trace: <IRQ> sctp6_rcv+0x38/0x60 net/sctp/ipv6.c:1109 ip6_protocol_deliver_rcu+0x2e9/0x1ca0 net/ipv6/ip6_input.c:422 ip6_input_finish+0x62/0x170 net/ipv6/ip6_input.c:463 NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:472 dst_input include/net/dst.h:460 [inline] ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ipv6_rcv+0x28c/0x3c0 net/ipv6/ip6_input.c:297

Affected products

Linux kernel: from 4.8 before 4.14.249; from 4.15 before 4.19.209; from 4.20 before 5.4.151; from 5.5 before 5.10.71; from 5.11 before 5.14.10; 5.15-rc1, 5.15-rc2, 5.15-rc3 — fixed in 4.14.249, 4.19.209, 5.10.71, 5.14.10, 5.4.151

How to fix

Upgrade to a fixed version: Linux kernel 4.14.249, 4.19.209, 5.10.71, 5.14.10. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2021-47397 or the next vulnerability affects your stack