{"id":"CVE-2026-98021","revision":"83a42e3406d04fe4b07da17db803d819","records":[{"revision":"83a42e3406d04fe4b07da17db803d819","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-98021","aliases":[],"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":0,"publishedAt":"2026-09-25T10:23:41.505+00:00","modifiedAt":"2026-10-21T12:54:05.196+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"Documentation/netlink/specs/rt-link.yaml\",\n                        \"net/core/rtnetlink.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"38f7b870d4a6a5d3ec21557e849620cb7d032965\",\n                            \"lessThan\": \"26ee5f99ffe7ab98e635071290eff14192e9e34a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"38f7b870d4a6a5d3ec21557e849620cb7d032965\",\n                            \"lessThan\": \"45ca9f59b6c7ea70e0a17054902b8a556913db34\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"38f7b870d4a6a5d3ec21557e849620cb7d032965\",\n                            \"lessThan\": \"2fd0880f0272ec022906a05587fd91416ebecc38\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"38f7b870d4a6a5d3ec21557e849620cb7d032965\",\n                            \"lessThan\": \"a638a2625aa83160a394abe8e8b2e524a80c771b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"38f7b870d4a6a5d3ec21557e849620cb7d032965\",\n                            \"lessThan\": \"1aa9e143bf51405665a793d4cc925e1c4f0c5922\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"Documentation/netlink/specs/rt-link.yaml\",\n                        \"net/core/rtnetlink.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"2.6.23\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"2.6.23\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.160\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.111\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.53\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.7\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/26ee5f99ffe7ab98e635071290eff14192e9e34a","https://git.kernel.org/stable/c/45ca9f59b6c7ea70e0a17054902b8a556913db34","https://git.kernel.org/stable/c/2fd0880f0272ec022906a05587fd91416ebecc38","https://git.kernel.org/stable/c/a638a2625aa83160a394abe8e8b2e524a80c771b","https://git.kernel.org/stable/c/1aa9e143bf51405665a793d4cc925e1c4f0c5922"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98021","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98021","identifiers":["CVE-2026-98021"]},"retained":false,"historicalAffected":[]}],"coverage":[]}