{"id":"CVE-2026-64576","state":"PUBLISHED","title":"nexthop: initialize extack in nh_res_bucket_migrate()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnexthop: initialize extack in nh_res_bucket_migrate()\n\nnh_res_bucket_migrate() passes an uninitialized netlink_ext_ack to\ncall_nexthop_res_bucket_notifiers(). When\nnh_notifier_res_bucket_info_init() fails (e.g. the kzalloc returns\n-ENOMEM), the error is propagated back before any notifier sets\nextack._msg, and the error path formats the stale pointer with\npr_err_ratelimited(\"%s\\n\", extack._msg). With CONFIG_INIT_STACK_NONE\nthis dereferences uninitialized stack memory:\n\n  Oops: general protection fault, probably for non-canonical address ...\n  KASAN: maybe wild-memory-access in range [...]\n  RIP: 0010:string (lib/vsprintf.c:730)\n   vsnprintf (lib/vsprintf.c:2945)\n   _printk (kernel/printk/printk.c:2504)\n   nh_res_bucket_migrate (net/ipv4/nexthop.c:1816)\n   nh_res_table_upkeep (net/ipv4/nexthop.c:1866)\n   rtm_new_nexthop (net/ipv4/nexthop.c:3323)\n   rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)\n   netlink_sendmsg (net/netlink/af_netlink.c:1900)\n  Kernel panic - not syncing: Fatal exception\n\nZero-initialize extack so _msg is NULL on error paths that never set it.","publishedAt":"2026-08-05T08:09:32.529Z","updatedAt":"2026-10-19T20:48:42.772Z","severity":{"score":7.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"eacd2e2117e8682f937967fda1022e7f1c22d91a","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"37bbd7e1d8df0bec3d187e961783e20c30533d2c","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"c0936c131a71657afc635d0db2ab096d15d473e1","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"3081702ea5aca0aeed9c1ade8eadf6cde8db6b7d","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"d536bf205c71f700f6de2086038c3e1d77724715","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"18506d7263768d76ac8e057ba55a4d9da50aad66","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"6347c5314cee49f364aaf2e40ff15415a57a116e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/nexthop.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.13","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.148","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.101","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","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/nexthop.c"]}],"references":["https://git.kernel.org/stable/c/eacd2e2117e8682f937967fda1022e7f1c22d91a","https://git.kernel.org/stable/c/37bbd7e1d8df0bec3d187e961783e20c30533d2c","https://git.kernel.org/stable/c/c0936c131a71657afc635d0db2ab096d15d473e1","https://git.kernel.org/stable/c/3081702ea5aca0aeed9c1ade8eadf6cde8db6b7d","https://git.kernel.org/stable/c/d536bf205c71f700f6de2086038c3e1d77724715","https://git.kernel.org/stable/c/18506d7263768d76ac8e057ba55a4d9da50aad66","https://git.kernel.org/stable/c/6347c5314cee49f364aaf2e40ff15415a57a116e"],"weaknesses":["CWE-457"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64576.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64576","state":"PUBLISHED","datePublished":"2026-08-05T08:09:32.529Z","dateUpdated":"2026-10-19T20:48:42.772Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.798Z"},"containers":{"cna":{"title":"nexthop: initialize extack in nh_res_bucket_migrate()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnexthop: initialize extack in nh_res_bucket_migrate()\n\nnh_res_bucket_migrate() passes an uninitialized netlink_ext_ack to\ncall_nexthop_res_bucket_notifiers(). When\nnh_notifier_res_bucket_info_init() fails (e.g. the kzalloc returns\n-ENOMEM), the error is propagated back before any notifier sets\nextack._msg, and the error path formats the stale pointer with\npr_err_ratelimited(\"%s\\n\", extack._msg). With CONFIG_INIT_STACK_NONE\nthis dereferences uninitialized stack memory:\n\n  Oops: general protection fault, probably for non-canonical address ...\n  KASAN: maybe wild-memory-access in range [...]\n  RIP: 0010:string (lib/vsprintf.c:730)\n   vsnprintf (lib/vsprintf.c:2945)\n   _printk (kernel/printk/printk.c:2504)\n   nh_res_bucket_migrate (net/ipv4/nexthop.c:1816)\n   nh_res_table_upkeep (net/ipv4/nexthop.c:1866)\n   rtm_new_nexthop (net/ipv4/nexthop.c:3323)\n   rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)\n   netlink_sendmsg (net/netlink/af_netlink.c:1900)\n  Kernel panic - not syncing: Fatal exception\n\nZero-initialize extack so _msg is NULL on error paths that never set it."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"eacd2e2117e8682f937967fda1022e7f1c22d91a","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"37bbd7e1d8df0bec3d187e961783e20c30533d2c","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"c0936c131a71657afc635d0db2ab096d15d473e1","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"3081702ea5aca0aeed9c1ade8eadf6cde8db6b7d","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"d536bf205c71f700f6de2086038c3e1d77724715","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"18506d7263768d76ac8e057ba55a4d9da50aad66","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","status":"affected","lessThan":"6347c5314cee49f364aaf2e40ff15415a57a116e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/nexthop.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.13","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.148","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.101","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","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/nexthop.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/eacd2e2117e8682f937967fda1022e7f1c22d91a"},{"url":"https://git.kernel.org/stable/c/37bbd7e1d8df0bec3d187e961783e20c30533d2c"},{"url":"https://git.kernel.org/stable/c/c0936c131a71657afc635d0db2ab096d15d473e1"},{"url":"https://git.kernel.org/stable/c/3081702ea5aca0aeed9c1ade8eadf6cde8db6b7d"},{"url":"https://git.kernel.org/stable/c/d536bf205c71f700f6de2086038c3e1d77724715"},{"url":"https://git.kernel.org/stable/c/18506d7263768d76ac8e057ba55a4d9da50aad66"},{"url":"https://git.kernel.org/stable/c/6347c5314cee49f364aaf2e40ff15415a57a116e"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","baseScore":7.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - Triggered via local RTM_NEWNEXTHOP over rtnetlink (sendmsg → rtnetlink_rcv_msg → rtm_new_nexthop → nh_res_table_upkeep → nh_res_bucket_migrate), not by processing remote packets.\nAC:L - An attacker can create resilient nexthop groups, ensure notifiers are registered (e.g. VXLAN pernet init), force bucket migration, and induce the kzalloc -ENOMEM path; stack contents are groomable, with no attacker-independent condition required.\nPR:L - rtnetlink_rcv_msg requires CAP_NET_ADMIN via netlink_net_capable() against the socket netns user_ns, which an unprivileged user obtains with unshare -Urn, so privileges are Low not High.\nUI:N - The attacker issues the netlink nexthop configuration and triggers migration themselves; no victim action is required.\nS:U - Impact stays within the host kernel networking authority; this is a local DoS/disclosure bug, not a VM escape, IOMMU bypass, or other cross-boundary scope change.\nC:H - pr_err_ratelimited(\"%s\") dereferences an uninitialized extack._msg pointer as a C string, enabling an attacker-groomable wild kernel read into the log, consistent with treating unbounded wild/OOB reads as Confidentiality High.\nI:N - The defect only reads through the stale _msg pointer for printing; there is no write, free, or other memory-corruption integrity primitive.\nA:H - The wild %s dereference causes a general protection fault / KASAN wild-memory-access and kernel panic, as shown in the fix commit report, so Availability is High."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-19T16:28:57.222Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"5.15.216"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"6.1.183"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"6.6.148"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"6.12.101"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"6.18.42"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"7.1.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-64576","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:43:11.555389Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-457","lang":"en","type":"CWE","description":"CWE-457 Use of Uninitialized Variable"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:48:42.772Z"}}]}}}