{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64576","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-07-19T15:36:31.798Z","datePublished":"2026-08-05T08:09:32.529Z","dateUpdated":"2026-08-19T16:28:57.222Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-19T16:28:57.222Z"},"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."}],"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."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/nexthop.c"],"versions":[{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","lessThan":"eacd2e2117e8682f937967fda1022e7f1c22d91a","status":"affected","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","lessThan":"37bbd7e1d8df0bec3d187e961783e20c30533d2c","status":"affected","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","lessThan":"c0936c131a71657afc635d0db2ab096d15d473e1","status":"affected","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","lessThan":"3081702ea5aca0aeed9c1ade8eadf6cde8db6b7d","status":"affected","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","lessThan":"d536bf205c71f700f6de2086038c3e1d77724715","status":"affected","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","lessThan":"18506d7263768d76ac8e057ba55a4d9da50aad66","status":"affected","versionType":"git"},{"version":"7c37c7e00411b3d1e0c5292368317aca69d1f324","lessThan":"6347c5314cee49f364aaf2e40ff15415a57a116e","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/nexthop.c"],"versions":[{"version":"5.13","status":"affected"},{"version":"0","lessThan":"5.13","status":"unaffected","versionType":"semver"},{"version":"5.15.216","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.183","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.148","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.101","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.42","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1.6","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"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"}]}]}],"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"}],"title":"nexthop: initialize extack in nh_res_bucket_migrate()","x_generator":{"engine":"bippy-1.2.0"}}}}