{"api_version":"1","generated_at":"2026-09-25T12:40:49+00:00","cve":"CVE-2026-98021","urls":{"html":"https://cve.report/CVE-2026-98021","api":"https://cve.report/api/cve/CVE-2026-98021.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98021","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98021"},"summary":{"title":"net: reject oversized tx_queue_len at netlink parse time","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: reject oversized tx_queue_len at netlink parse time\n\nrtnl_create_link() assigns IFLA_TXQLEN directly to dev->tx_queue_len\nwithout going through netif_change_tx_queue_len(), so a device created\nwith \"ip link add ... txqueuelen 500000\" bypasses the S16_MAX cap and\nstill triggers the oversized ring allocations in pfifo_fast, tun and\ntap. The veth peer nest (rtnl_nla_parse_ifinfomsg()) and the\nRTM_NEWLINK-on-existing-device path reach the same sinks.\n\nEnforce the cap in ifla_policy instead: IFLA_TXQLEN becomes\nNLA_POLICY_FULL_RANGE(NLA_U32, &txqlen_range) with\ntxqlen_range = { .min = 0, .max = S16_MAX }. All netlink consumers\nparse against this policy - rtnl_setlink(), rtnl_newlink() (create\nand change), and the veth peer nest - so every netlink path is capped\nat parse time and rejects the attribute with -ERANGE plus a proper\n\"integer out of range\" extack message before any device state is\nmodified (the RTM_SETLINK half-application wart is gone with it).\n\nDocument the bound in the rt-link.yaml netlink spec.\n\nConditions to recreate the bug:\n- CONFIG_NET_SCHED=y, CONFIG_VETH=y, CONFIG_USER_NS=y, CONFIG_NET_NS=y.\n- Unprivileged user in a fresh user+net namespace (unshare -Urn):\n  ip link add v0 txqueuelen 500000 type veth peer name v1\n  -> on the fixed kernel this is rejected with -ERANGE (\"integer out\n  of range\" extack) instead of installing an oversized tx_queue_len\n  that later inflates pfifo_fast/tun/tap ring allocations.\n- ip link set v0 txqueuelen 500000 is likewise rejected at parse time.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-25 11:17:30","updated_at":"2026-09-25 11:17:30"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/45ca9f59b6c7ea70e0a17054902b8a556913db34","name":"https://git.kernel.org/stable/c/45ca9f59b6c7ea70e0a17054902b8a556913db34","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a638a2625aa83160a394abe8e8b2e524a80c771b","name":"https://git.kernel.org/stable/c/a638a2625aa83160a394abe8e8b2e524a80c771b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1aa9e143bf51405665a793d4cc925e1c4f0c5922","name":"https://git.kernel.org/stable/c/1aa9e143bf51405665a793d4cc925e1c4f0c5922","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2fd0880f0272ec022906a05587fd91416ebecc38","name":"https://git.kernel.org/stable/c/2fd0880f0272ec022906a05587fd91416ebecc38","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98021","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98021","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 38f7b870d4a6a5d3ec21557e849620cb7d032965 45ca9f59b6c7ea70e0a17054902b8a556913db34 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 38f7b870d4a6a5d3ec21557e849620cb7d032965 2fd0880f0272ec022906a05587fd91416ebecc38 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 38f7b870d4a6a5d3ec21557e849620cb7d032965 a638a2625aa83160a394abe8e8b2e524a80c771b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 38f7b870d4a6a5d3ec21557e849620cb7d032965 1aa9e143bf51405665a793d4cc925e1c4f0c5922 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.23","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.23 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.111 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.53 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.7 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["Documentation/netlink/specs/rt-link.yaml","net/core/rtnetlink.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"45ca9f59b6c7ea70e0a17054902b8a556913db34","status":"affected","version":"38f7b870d4a6a5d3ec21557e849620cb7d032965","versionType":"git"},{"lessThan":"2fd0880f0272ec022906a05587fd91416ebecc38","status":"affected","version":"38f7b870d4a6a5d3ec21557e849620cb7d032965","versionType":"git"},{"lessThan":"a638a2625aa83160a394abe8e8b2e524a80c771b","status":"affected","version":"38f7b870d4a6a5d3ec21557e849620cb7d032965","versionType":"git"},{"lessThan":"1aa9e143bf51405665a793d4cc925e1c4f0c5922","status":"affected","version":"38f7b870d4a6a5d3ec21557e849620cb7d032965","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["Documentation/netlink/specs/rt-link.yaml","net/core/rtnetlink.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.23"},{"lessThan":"2.6.23","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.111","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.53","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.7","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.111","versionStartIncluding":"2.6.23","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.53","versionStartIncluding":"2.6.23","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.7","versionStartIncluding":"2.6.23","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc3","versionStartIncluding":"2.6.23","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: reject oversized tx_queue_len at netlink parse time\n\nrtnl_create_link() assigns IFLA_TXQLEN directly to dev->tx_queue_len\nwithout going through netif_change_tx_queue_len(), so a device created\nwith \"ip link add ... txqueuelen 500000\" bypasses the S16_MAX cap and\nstill triggers the oversized ring allocations in pfifo_fast, tun and\ntap. The veth peer nest (rtnl_nla_parse_ifinfomsg()) and the\nRTM_NEWLINK-on-existing-device path reach the same sinks.\n\nEnforce the cap in ifla_policy instead: IFLA_TXQLEN becomes\nNLA_POLICY_FULL_RANGE(NLA_U32, &txqlen_range) with\ntxqlen_range = { .min = 0, .max = S16_MAX }. All netlink consumers\nparse against this policy - rtnl_setlink(), rtnl_newlink() (create\nand change), and the veth peer nest - so every netlink path is capped\nat parse time and rejects the attribute with -ERANGE plus a proper\n\"integer out of range\" extack message before any device state is\nmodified (the RTM_SETLINK half-application wart is gone with it).\n\nDocument the bound in the rt-link.yaml netlink spec.\n\nConditions to recreate the bug:\n- CONFIG_NET_SCHED=y, CONFIG_VETH=y, CONFIG_USER_NS=y, CONFIG_NET_NS=y.\n- Unprivileged user in a fresh user+net namespace (unshare -Urn):\n  ip link add v0 txqueuelen 500000 type veth peer name v1\n  -> on the fixed kernel this is rejected with -ERANGE (\"integer out\n  of range\" extack) instead of installing an oversized tx_queue_len\n  that later inflates pfifo_fast/tun/tap ring allocations.\n- ip link set v0 txqueuelen 500000 is likewise rejected at parse time."}],"providerMetadata":{"dateUpdated":"2026-09-25T10:23:41.505Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/45ca9f59b6c7ea70e0a17054902b8a556913db34"},{"url":"https://git.kernel.org/stable/c/2fd0880f0272ec022906a05587fd91416ebecc38"},{"url":"https://git.kernel.org/stable/c/a638a2625aa83160a394abe8e8b2e524a80c771b"},{"url":"https://git.kernel.org/stable/c/1aa9e143bf51405665a793d4cc925e1c4f0c5922"}],"title":"net: reject oversized tx_queue_len at netlink parse time","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98021","datePublished":"2026-09-25T10:23:41.505Z","dateReserved":"2026-09-25T10:19:56.069Z","dateUpdated":"2026-09-25T10:23:41.505Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-25 11:17:30","lastModifiedDate":"2026-09-25 11:17:30","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98021","Ordinal":"1","Title":"net: reject oversized tx_queue_len at netlink parse time","CVE":"CVE-2026-98021","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98021","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: reject oversized tx_queue_len at netlink parse time\n\nrtnl_create_link() assigns IFLA_TXQLEN directly to dev->tx_queue_len\nwithout going through netif_change_tx_queue_len(), so a device created\nwith \"ip link add ... txqueuelen 500000\" bypasses the S16_MAX cap and\nstill triggers the oversized ring allocations in pfifo_fast, tun and\ntap. The veth peer nest (rtnl_nla_parse_ifinfomsg()) and the\nRTM_NEWLINK-on-existing-device path reach the same sinks.\n\nEnforce the cap in ifla_policy instead: IFLA_TXQLEN becomes\nNLA_POLICY_FULL_RANGE(NLA_U32, &txqlen_range) with\ntxqlen_range = { .min = 0, .max = S16_MAX }. All netlink consumers\nparse against this policy - rtnl_setlink(), rtnl_newlink() (create\nand change), and the veth peer nest - so every netlink path is capped\nat parse time and rejects the attribute with -ERANGE plus a proper\n\"integer out of range\" extack message before any device state is\nmodified (the RTM_SETLINK half-application wart is gone with it).\n\nDocument the bound in the rt-link.yaml netlink spec.\n\nConditions to recreate the bug:\n- CONFIG_NET_SCHED=y, CONFIG_VETH=y, CONFIG_USER_NS=y, CONFIG_NET_NS=y.\n- Unprivileged user in a fresh user+net namespace (unshare -Urn):\n  ip link add v0 txqueuelen 500000 type veth peer name v1\n  -> on the fixed kernel this is rejected with -ERANGE (\"integer out\n  of range\" extack) instead of installing an oversized tx_queue_len\n  that later inflates pfifo_fast/tun/tap ring allocations.\n- ip link set v0 txqueuelen 500000 is likewise rejected at parse time.","Type":"Description","Title":"net: reject oversized tx_queue_len at netlink parse time"}]}}}