{"id":"CVE-2026-74550","state":"PUBLISHED","title":"net: do not send ICMP/NDISC Redirects when peer allocation fails","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: do not send ICMP/NDISC Redirects when peer allocation fails\n\nWhen inet_getpeer_v4() or inet_getpeer_v6() fails to allocate a peer entry\nunder memory pressure or tree size caps, redirect handlers previously fell\nback to sending un-rate-limited ICMP/NDISC Redirect messages.\n\nIn IPv4, ip_rt_send_redirect() called icmp_send() directly when peer == NULL.\nIn IPv6, ip6_forward() and ndisc_send_redirect() passed a NULL peer into\ninet_peer_xrlim_allow(), which returned true when peer == NULL.\n\nBecause ICMP/NDISC Redirects are not part of the default global rate limit\nmask (sysctl_icmp_ratemask), sending redirects when peer == NULL creates\nan un-rate-limited ICMP packet storm.\n\nFix this by failing closed in ip_rt_send_redirect(), ip6_forward(), and\nndisc_send_redirect() when peer is NULL.","publishedAt":"2026-08-15T12:27:57.615Z","updatedAt":"2026-10-16T19:05:55.243Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"92d8682926342d2b6aa5b2ecc02221e00e1573a0","status":"affected","lessThan":"c0adf8b4247bcc5a145a25c1929006eb392580bb","versionType":"git"},{"version":"92d8682926342d2b6aa5b2ecc02221e00e1573a0","status":"affected","lessThan":"f5ecaa7ea7686fa7ecdb6affc9d3a9a42e4524b1","versionType":"git"},{"version":"92d8682926342d2b6aa5b2ecc02221e00e1573a0","status":"affected","lessThan":"21666f7af49a90ef44d474916b8ef4402dfd74f5","versionType":"git"},{"version":"92d8682926342d2b6aa5b2ecc02221e00e1573a0","status":"affected","lessThan":"5ec5f00fc606a6df8434948c4552b3cb1176595d","versionType":"git"},{"version":"92d8682926342d2b6aa5b2ecc02221e00e1573a0","status":"affected","lessThan":"828f6670d110ff2bf44c743037b38badc315704c","versionType":"git"},{"version":"92d8682926342d2b6aa5b2ecc02221e00e1573a0","status":"affected","lessThan":"dbc3791e3b2472e1ccc08947e0f83b443470ff4f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/route.c","net/ipv6/ip6_output.c","net/ipv6/ndisc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.39","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.39","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.151","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.103","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.44","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.8","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/route.c","net/ipv6/ip6_output.c","net/ipv6/ndisc.c"]}],"references":["https://git.kernel.org/stable/c/c0adf8b4247bcc5a145a25c1929006eb392580bb","https://git.kernel.org/stable/c/f5ecaa7ea7686fa7ecdb6affc9d3a9a42e4524b1","https://git.kernel.org/stable/c/21666f7af49a90ef44d474916b8ef4402dfd74f5","https://git.kernel.org/stable/c/5ec5f00fc606a6df8434948c4552b3cb1176595d","https://git.kernel.org/stable/c/828f6670d110ff2bf44c743037b38badc315704c","https://git.kernel.org/stable/c/dbc3791e3b2472e1ccc08947e0f83b443470ff4f"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74550.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74550","state":"PUBLISHED","datePublished":"2026-08-15T12:27:57.615Z","dateUpdated":"2026-10-16T19:05:55.243Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.915Z"},"containers":{"cna":{"title":"net: do not send ICMP/NDISC Redirects when peer allocation fails","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: do not send ICMP/NDISC Redirects when peer allocation fails\n\nWhen inet_getpeer_v4() or inet_getpeer_v6() fails to allocate a peer entry\nunder memory pressure or tree size caps, redirect handlers previously fell\nback to sending un-rate-limited ICMP/NDISC Redirect messages.\n\nIn IPv4, ip_rt_send_redirect() called icmp_send() directly when peer == NULL.\nIn IPv6, ip6_forward() and ndisc_send_redirect() passed a NULL peer into\ninet_peer_xrlim_allow(), which returned true when peer == NULL.\n\nBecause ICMP/NDISC Redirects are not part of the default global rate limit\nmask (sysctl_icmp_ratemask), sending redirects when peer == NULL creates\nan un-rate-limited ICMP packet storm.\n\nFix this by failing closed in ip_rt_send_redirect(), ip6_forward(), and\nndisc_send_redirect() when peer is NULL."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"92d8682926342d2b6aa5b2ecc02221e00e1573a0","status":"affected","lessThan":"c0adf8b4247bcc5a145a25c1929006eb392580bb","versionType":"git"},{"version":"92d8682926342d2b6aa5b2ecc02221e00e1573a0","status":"affected","lessThan":"f5ecaa7ea7686fa7ecdb6affc9d3a9a42e4524b1","versionType":"git"},{"version":"92d8682926342d2b6aa5b2ecc02221e00e1573a0","status":"affected","lessThan":"21666f7af49a90ef44d474916b8ef4402dfd74f5","versionType":"git"},{"version":"92d8682926342d2b6aa5b2ecc02221e00e1573a0","status":"affected","lessThan":"5ec5f00fc606a6df8434948c4552b3cb1176595d","versionType":"git"},{"version":"92d8682926342d2b6aa5b2ecc02221e00e1573a0","status":"affected","lessThan":"828f6670d110ff2bf44c743037b38badc315704c","versionType":"git"},{"version":"92d8682926342d2b6aa5b2ecc02221e00e1573a0","status":"affected","lessThan":"dbc3791e3b2472e1ccc08947e0f83b443470ff4f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/route.c","net/ipv6/ip6_output.c","net/ipv6/ndisc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.39","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.39","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.151","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.103","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.44","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.8","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/route.c","net/ipv6/ip6_output.c","net/ipv6/ndisc.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/c0adf8b4247bcc5a145a25c1929006eb392580bb"},{"url":"https://git.kernel.org/stable/c/f5ecaa7ea7686fa7ecdb6affc9d3a9a42e4524b1"},{"url":"https://git.kernel.org/stable/c/21666f7af49a90ef44d474916b8ef4402dfd74f5"},{"url":"https://git.kernel.org/stable/c/5ec5f00fc606a6df8434948c4552b3cb1176595d"},{"url":"https://git.kernel.org/stable/c/828f6670d110ff2bf44c743037b38badc315704c"},{"url":"https://git.kernel.org/stable/c/dbc3791e3b2472e1ccc08947e0f83b443470ff4f"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The flaw is in IPv4/IPv6 packet forwarding paths (ip_forward/ip6_forward) reached when a remote host sends IP traffic processed by a forwarding router; this is standard net stack input handling, not a local-only API.\nAC:L - An attacker can reliably trigger redirect-eligible forwarded packets, flood unique source/destination addresses to stress inet_peer allocation, and induce memory pressure so peer allocation fails, controlling the conditions needed for the un-rate-limited redirect storm.\nPR:N - Exploitation requires only the ability to send IP packets to a forwarding host; no local account, capabilities, or authentication on the victim is needed.\nUI:N - No victim user action is required; the redirect storm is triggered entirely by attacker-sent network packets processed during kernel forwarding.\nS:U - Impact is confined to the kernel/network stack of the targeted forwarding system and its network availability; it does not cross VM, container, or IOMMU security boundaries.\nC:N - The bug bypasses redirect rate limiting to generate ICMP/NDISC storms; it does not involve memory corruption, out-of-bounds access, or unintended disclosure of sensitive kernel memory.\nI:N - The vulnerability causes excessive transmission of otherwise-valid redirect messages; it does not grant arbitrary data modification, code execution, or attacker-controlled corruption of kernel or application state.\nA:H - When peer allocation fails, ICMP/NDISC Redirects are sent without any rate limit (excluded from sysctl_icmp_ratemask), enabling a sustained packet storm that can exhaust CPU, memory, and bandwidth and deny service to the router and adjacent networks."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-19T16:38:44.870Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"6.1.183"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"6.6.151"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"6.12.103"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"6.18.44"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"7.1.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.39","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-74550","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T18:59:55.162783Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:05:55.243Z"}}]}}}