{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-98022", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-98022", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-09-25T10:23:42.116Z", "updatedAt": "2026-10-19T09:12:27.416Z", "importedAt": "2026-10-24T01:58:41.756Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "net: cap tx_queue_len at S16_MAX to prevent oversized ring allocations", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: cap tx_queue_len at S16_MAX to prevent oversized ring allocations\n\nSeveral subsystems allocate ring buffers sized by dev->tx_queue_len\nwith no upper bound. An unprivileged user (via unshare -Urn) can set a\nhuge tx_queue_len and exhaust global memory with ring allocations:\n\n- pfifo_fast: pfifo_fast_init() and pfifo_fast_change_tx_queue_len()\n allocate 3 skb_array rings of tx_queue_len entries each.\n- tun: tun_queue_resize() and the queue-attach path resize ptr_rings\n to tx_queue_len on the NETDEV_CHANGE_TX_QUEUE_LEN notifier.\n- tap (macvtap/ipvtap): tap_queue_resize() and tap_init() resize/init\n ptr_rings to tx_queue_len on the same notifier.\n\nnetif_change_tx_queue_len() is the single entry point for IFLA_TXQLEN,\nsysfs, and the SIOCSIFTXQLEN ioctl. Cap new_len at S16_MAX (32767)\nthere so the oversized value is rejected at set time. This takes\neffect whether the device is up or down, before dev->tx_queue_len is\nwritten, before any notifier fires, and before any ring is allocated.\nThe \"> S16_MAX\" check also subsumes the previous unsigned-long\ntruncation test, and a negative ifr_qlen from the ioctl lands far\nabove the cap after conversion, so both old failure modes are covered\nby the one comparison.\n\ntx_queue_len is ambigious: both a per-ring sizing multiplier and a\ndefault queue-length/limit knob for consumers that allocate\nnothing at set time (pfifo/bfifo/gred/plug/sfb limits, htb\ndirect_qlen, qfq max_classes, teql). 32767 is chosen as the largest\nvalue NLA_POLICY_FULL_RANGE can express for the u32 IFLA_TXQLEN\npolicy in patch 2/3 while staying a legitimate queue length on\nhigh-BDP paths; the ring-memory trade-off of a shared knob is\ndisclosed below.\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- pfifo_fast: create veth pairs, set tx_queue_len to 500000, attach\n mq+pfifo_fast. ~28 iterations OOMs a 2GB guest.\n- tun: create 50 tun devices with IFF_MULTI_QUEUE, set tx_queue_len to\n 500000, open 8 queues each. ~1.6GB of ptr_ring allocations OOMs a\n 512MB guest.\n- tap: same as tun with IFF_TAP. ~960MB OOMs a 512MB guest.\n- On the fixed kernel the oversized tx_queue_len is rejected with\n -ERANGE at set time (all four paths: RTM_SETLINK, RTM_NEWLINK\n create, sysfs, ioctl - the latter two via this check, the former\n two via this check and the 2/3 parse policy respectively).", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "status": "affected", "versionType": "git", "lessThan": "24d02c909a1725ab9eceb92db7d02e4e841f17ca" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "status": "affected", "versionType": "git", "lessThan": "5e5591a0f33f7c11bf1d338dbb6c5072575de64c" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "status": "affected", "versionType": "git", "lessThan": "c8d4060610c69645733c92d94fceb4b93808ac4d" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "status": "affected", "versionType": "git", "lessThan": "c2362c500931e5bd1826bce34e9ce28af80e7541" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "status": "affected", "versionType": "git", "lessThan": "81c0e02076989743a603806a5a4f44d2c40dc01f" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "status": "affected", "versionType": "git", "lessThan": "081340cf70a789b94b4174af54a63ffd49677a4e" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "status": "affected", "versionType": "git", "lessThan": "a03b927bae4af5c23fd5315a237855c17cc8f422" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "status": "affected", "versionType": "git", "lessThan": "66ab4c59b74db7ab53a1c9083feaaede393a96a0" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "4.16", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "4.16" }, { "version": "5.10.271", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.222", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.189", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.158", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.111", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.53", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.2.7", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.2.*" }, { "version": "7.3", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }