{"id":"CVE-2026-98021","title":"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_que…","summary":"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_que…","severity":"medium","vendor":"Linux","product":"Linux","affected":["Linux >= 38f7b870d4a6a5d3ec21557e849620cb7d032965 < 45ca9f59b6c7ea70e0a17054902b8a556913db34","Linux >= 38f7b870d4a6a5d3ec21557e849620cb7d032965 < 2fd0880f0272ec022906a05587fd91416ebecc38","Linux >= 38f7b870d4a6a5d3ec21557e849620cb7d032965 < a638a2625aa83160a394abe8e8b2e524a80c771b","Linux >= 38f7b870d4a6a5d3ec21557e849620cb7d032965 < 1aa9e143bf51405665a793d4cc925e1c4f0c5922","Linux 2.6.23"],"published":"2026-09-25","updated":"2026-09-25","sourceUpdated":"2026-09-25T11:17:30.613","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-98021","references":[{"url":"https://git.kernel.org/stable/c/1aa9e143bf51405665a793d4cc925e1c4f0c5922","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2fd0880f0272ec022906a05587fd91416ebecc38","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/45ca9f59b6c7ea70e0a17054902b8a556913db34","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a638a2625aa83160a394abe8e8b2e524a80c771b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98021.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-98021"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2541299"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98021"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98021"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98021.mbox"},{"url":"https://git.kernel.org/stable/c/26ee5f99ffe7ab98e635071290eff14192e9e34a"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"ingestedAt":"2026-09-25T11:06:38.855Z","epss":0.00176,"epssPercentile":0.07092,"cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-1284"],"slug":"CVE-2026-98021","body":"## Overview\n\nIn 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Low · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98021.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":212440,"id":"CVE-2026-98021","ts":1790668182575,"field":"cvss","old":null,"new":"5.5"},{"seq":212439,"id":"CVE-2026-98021","ts":1790668182575,"field":"severity","old":"none","new":"medium"}]}