CVE-2026-23398Medium· 5.5▾ TwilightPoC availableIn the Linux kernel, the following vulnerability has been resolved: icmp: fix NULL pointer dereference in icmp_tag_validation() icmp_tag_validation() unconditionally dereferences the result of rcu_dereference(inet_protos[proto]) withou…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 30.3 · likelihood 0 · exploitation 12
A public proof-of-concept already exists for this vulnerability — see Exploit availability below.
Public exploit / PoC code seen in 1 source. Availability, not in-the-wild use.
Exploit-prediction probability, daily snapshots since Sep 8.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.1%
Last analysed / modified upstream
— → 5.5
none → medium
0.1% → 0.1%
2 GitHub repos (last check)
In the Linux kernel, the following vulnerability has been resolved:
icmp: fix NULL pointer dereference in icmp_tag_validation()
icmp_tag_validation() unconditionally dereferences the result of rcu_dereference(inet_protos[proto]) without checking for NULL. The inet_protos[] array is sparse -- only about 15 of 256 protocol numbers have registered handlers. When ip_no_pmtu_disc is set to 3 (hardened PMTU mode) and the kernel receives an ICMP Fragmentation Needed error with a quoted inner IP header containing an unregistered protocol number, the NULL dereference causes a kernel panic in softirq context.
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:icmp_unreach (net/ipv4/icmp.c:1085 net/ipv4/icmp.c:1143) Call Trace: <IRQ> icmp_rcv (net/ipv4/icmp.c:1527) ip_protocol_deliver_rcu (net/ipv4/ip_input.c:207) ip_local_deliver_finish (net/ipv4/ip_input.c:242) ip_local_deliver (net/ipv4/ip_input.c:262) ip_rcv (net/ipv4/ip_input.c:573) __netif_receive_skb_one_core (net/core/dev.c:6164) process_backlog (net/core/dev.c:6628) handle_softirqs (kernel/softirq.c:561) </IRQ>
Add a NULL check before accessing icmp_strict_tag_validation. If the protocol has no registered handler, return false since it cannot perform strict tag validation.
linux_kernel >= 3.14.1, < 5.10.253linux_kernel >= 5.11, < 5.15.203linux_kernel >= 5.16, < 6.1.167linux_kernel >= 6.2, < 6.6.130linux_kernel >= 6.7, < 6.12.78linux_kernel >= 6.13, < 6.18.20linux_kernel >= 6.19, < 6.19.10linux_kernel = 3.14linux_kernel = 7.0Upgrade past the affected range:
linux_kernel 6.19.10Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
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