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CVE-2026-98022

Vulnérabilité non évaluée dans Linux (Linux)

CVSS 0.0 · Non évaluée
EPSS 0.2%
Linux•Linux•Versions : <=6.1.*, <=6.12.*, 7.2.7, <4.16, 6.18.53, 6a643ddb5624be7e0694d49f5765a8d41c1ab6d0, <c2362c500931e5bd1826bce34e9ce28af80e7541, 0, <24d02c909a1725ab9eceb92db7d02e4e841f17ca, <a03b927bae4af5c23fd5315a237855c17cc8f422, 5.10.271, 6.6.158, <=5.10.*, <=6.6.*, 6.1.189, <5e5591a0f33f7c11bf1d338dbb6c5072575de64c, <81c0e02076989743a603806a5a4f44d2c40dc01f, <c8d4060610c69645733c92d94fceb4b93808ac4d, <=6.18.*, 5.15.222, <=7.2.*, 4.16, <66ab4c59b74db7ab53a1c9083feaaede393a96a0, <=*, <=5.15.*, <081340cf70a789b94b4174af54a63ffd49677a4e, 6.12.111, 7.3

Description

In the Linux kernel, the following vulnerability has been resolved: net: cap tx_queue_len at S16_MAX to prevent oversized ring allocations Several subsystems allocate ring buffers sized by dev->tx_queue_len with no upper bound. An unprivileged user (via unshare -Urn) can set a huge tx_queue_len and exhaust global memory with ring allocations: - pfifo_fast: pfifo_fast_init() and pfifo_fast_change_tx_queue_len() allocate 3 skb_array rings of tx_queue_len entries each. - tun: tun_queue_resize() and the queue-attach path resize ptr_rings to tx_queue_len on the NETDEV_CHANGE_TX_QUEUE_LEN notifier. - tap (macvtap/ipvtap): tap_queue_resize() and tap_init() resize/init ptr_rings to tx_queue_len on the same notifier. netif_change_tx_queue_len() is the single entry point for IFLA_TXQLEN, sysfs, and the SIOCSIFTXQLEN ioctl. Cap new_len at S16_MAX (32767) there so the oversized value is rejected at set time. This takes effect whether the device is up or down, before dev->tx_queue_len is written, before any notifier fires, and before any ring is allocated. The "> S16_MAX" check also subsumes the previous unsigned-long truncation test, and a negative ifr_qlen from the ioctl lands far above the cap after conversion, so both old failure modes are covered by the one comparison. tx_queue_len is ambigious: both a per-ring sizing multiplier and a default queue-length/limit knob for consumers that allocate nothing at set time (pfifo/bfifo/gred/plug/sfb limits, htb direct_qlen, qfq max_classes, teql). 32767 is chosen as the largest value NLA_POLICY_FULL_RANGE can express for the u32 IFLA_TXQLEN policy in patch 2/3 while staying a legitimate queue length on high-BDP paths; the ring-memory trade-off of a shared knob is disclosed below. Conditions to recreate the bug: - CONFIG_NET_SCHED=y, CONFIG_VETH=y, CONFIG_USER_NS=y, CONFIG_NET_NS=y. - Unprivileged user in a fresh user+net namespace (unshare -Urn). - pfifo_fast: create veth pairs, set tx_queue_len to 500000, attach mq+pfifo_fast. ~28 iterations OOMs a 2GB guest. - tun: create 50 tun devices with IFF_MULTI_QUEUE, set tx_queue_len to 500000, open 8 queues each. ~1.6GB of ptr_ring allocations OOMs a 512MB guest. - tap: same as tun with IFF_TAP. ~960MB OOMs a 512MB guest. - On the fixed kernel the oversized tx_queue_len is rejected with -ERANGE at set time (all four paths: RTM_SETLINK, RTM_NEWLINK create, sysfs, ioctl - the latter two via this check, the former two via this check and the 2/3 parse policy respectively).

Gravité et risque d'exploitation

CVE-2026-98022 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.18 %, ce qui la place devant 6.8 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, <=6.12.*, 7.2.7, <4.16, 6.18.53, 6a643ddb5624be7e0694d49f5765a8d41c1ab6d0, <c2362c500931e5bd1826bce34e9ce28af80e7541, 0, <24d02c909a1725ab9eceb92db7d02e4e841f17ca, <a03b927bae4af5c23fd5315a237855c17cc8f422, 5.10.271, 6.6.158, <=5.10.*, <=6.6.*, 6.1.189, <5e5591a0f33f7c11bf1d338dbb6c5072575de64c, <81c0e02076989743a603806a5a4f44d2c40dc01f, <c8d4060610c69645733c92d94fceb4b93808ac4d, <=6.18.*, 5.15.222, <=7.2.*, 4.16, <66ab4c59b74db7ab53a1c9083feaaede393a96a0, <=*, <=5.15.*, <081340cf70a789b94b4174af54a63ffd49677a4e, 6.12.111, 7.3) est présent sur votre parc.
  • Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
  • À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
  • Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

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