{"id":"CVE-2026-23398","title":"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]) withou…","summary":"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]) withou…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-476"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 3.14.1, < 5.10.253","linux_kernel >= 5.11, < 5.15.203","linux_kernel >= 5.16, < 6.1.167","linux_kernel >= 6.2, < 6.6.130","linux_kernel >= 6.7, < 6.12.78","linux_kernel >= 6.13, < 6.18.20","linux_kernel >= 6.19, < 6.19.10","linux_kernel = 3.14","linux_kernel = 7.0"],"patched":["linux_kernel 6.19.10"],"published":"2026-03-26","updated":"2026-10-15","sourceUpdated":"2026-10-15T02:18:55.147","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-23398","references":[{"url":"https://git.kernel.org/stable/c/1e4e2f5e48cec0cccaea9815fb9486c084ba41e2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/1f9f2c6d4b2a613b7756fc5679c5116ba2ca0161","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/571d9d7b650f02d1e38c01128817868bceac9edd","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/614aefe56af8e13331e50220c936fc0689cf5675","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9647e99d2a617c355d2b378be0ff6d0e848fd579","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b61529c357f1ee4d64836eb142a542d2e7ad67ce","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d783fa413c702ff0f8f8bea63f862e28eeaf39e3","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d938dd5a0ad780c891ea3bc94cae7405f11e618a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-082556.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-457936.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-784472.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","exploit-available","cve.org"],"epss":0.00129,"epssPercentile":0.02559,"exploits":{"github":2,"githubRepos":["https://github.com/JohannesLks/CVE-2026-23398","https://github.com/zpol/cve-2026-23398-poc"],"checkedAt":"2026-10-27T17:02:45.057Z"},"exploitAvailable":true,"ingestedAt":"2026-09-08T15:33:26.992Z","slug":"CVE-2026-23398","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `linux_kernel >= 3.14.1, < 5.10.253`\n- `linux_kernel >= 5.11, < 5.15.203`\n- `linux_kernel >= 5.16, < 6.1.167`\n- `linux_kernel >= 6.2, < 6.6.130`\n- `linux_kernel >= 6.7, < 6.12.78`\n- `linux_kernel >= 6.13, < 6.18.20`\n- `linux_kernel >= 6.19, < 6.19.10`\n- `linux_kernel = 3.14`\n- `linux_kernel = 7.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.19.10`","depth":"twilight","depthScore":42,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":12,"ransomware":0},"changes":[{"seq":221679,"id":"CVE-2026-23398","ts":1792035318449,"field":"cvss","old":null,"new":"5.5"},{"seq":221678,"id":"CVE-2026-23398","ts":1792035318449,"field":"severity","old":"none","new":"medium"}]}