{"id":"CVE-2026-23398","summary":"icmp: fix NULL pointer dereference in icmp_tag_validation()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nicmp: fix NULL pointer dereference in icmp_tag_validation()\n\nicmp_tag_validation() unconditionally dereferences the result of\nrcu_dereference(inet_protos[proto]) without checking for NULL.\nThe inet_protos[] array is sparse -- only about 15 of 256 protocol\nnumbers have registered handlers. When ip_no_pmtu_disc is set to 3\n(hardened PMTU mode) and the kernel receives an ICMP Fragmentation\nNeeded error with a quoted inner IP header containing an unregistered\nprotocol number, the NULL dereference causes a kernel panic in\nsoftirq context.\n\n Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI\n KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]\n RIP: 0010:icmp_unreach (net/ipv4/icmp.c:1085 net/ipv4/icmp.c:1143)\n Call Trace:\n  \u003cIRQ\u003e\n  icmp_rcv (net/ipv4/icmp.c:1527)\n  ip_protocol_deliver_rcu (net/ipv4/ip_input.c:207)\n  ip_local_deliver_finish (net/ipv4/ip_input.c:242)\n  ip_local_deliver (net/ipv4/ip_input.c:262)\n  ip_rcv (net/ipv4/ip_input.c:573)\n  __netif_receive_skb_one_core (net/core/dev.c:6164)\n  process_backlog (net/core/dev.c:6628)\n  handle_softirqs (kernel/softirq.c:561)\n  \u003c/IRQ\u003e\n\nAdd a NULL check before accessing icmp_strict_tag_validation. If the\nprotocol has no registered handler, return false since it cannot\nperform strict tag validation.","modified":"2026-04-16T08:44:08.391020564Z","published":"2026-03-26T10:22:50.606Z","related":["SUSE-SU-2026:1342-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23398.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1e4e2f5e48cec0cccaea9815fb9486c084ba41e2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1f9f2c6d4b2a613b7756fc5679c5116ba2ca0161"},{"type":"WEB","url":"https://git.kernel.org/stable/c/614aefe56af8e13331e50220c936fc0689cf5675"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9647e99d2a617c355d2b378be0ff6d0e848fd579"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b61529c357f1ee4d64836eb142a542d2e7ad67ce"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d938dd5a0ad780c891ea3bc94cae7405f11e618a"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23398.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23398"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e"},{"fixed":"1f9f2c6d4b2a613b7756fc5679c5116ba2ca0161"},{"fixed":"b61529c357f1ee4d64836eb142a542d2e7ad67ce"},{"fixed":"9647e99d2a617c355d2b378be0ff6d0e848fd579"},{"fixed":"d938dd5a0ad780c891ea3bc94cae7405f11e618a"},{"fixed":"1e4e2f5e48cec0cccaea9815fb9486c084ba41e2"},{"fixed":"614aefe56af8e13331e50220c936fc0689cf5675"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23398.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.14.0"},{"fixed":"6.1.167"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.130"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.78"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.20"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.10"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23398.json"}}],"schema_version":"1.7.5"}