{"cve":"CVE-2026-23398","nvd":{"published":"2026-03-26T11:16:19.910","modified":"2026-10-15T02:18:55.147","status":"Modified","description":"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  <IRQ>\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  </IRQ>\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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-476"],"references":["https://git.kernel.org/stable/c/1e4e2f5e48cec0cccaea9815fb9486c084ba41e2","https://git.kernel.org/stable/c/1f9f2c6d4b2a613b7756fc5679c5116ba2ca0161","https://git.kernel.org/stable/c/571d9d7b650f02d1e38c01128817868bceac9edd","https://git.kernel.org/stable/c/614aefe56af8e13331e50220c936fc0689cf5675","https://git.kernel.org/stable/c/9647e99d2a617c355d2b378be0ff6d0e848fd579"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:28:18.033120106+00:00"},"epss":{"cve":"CVE-2026-23398","score":0.00129,"percentile":0.02556,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}