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CVE-2026-97984

Vulnérabilité non évaluée dans Linux (Linux)

CVSS 0.0 · Non évaluée
EPSS 0.2%
Linux•Linux•Versions : <=6.12.*, 7.2.7, <0ae10b6be49b425827659b23bcce498f80eb7182, 6.18.53, 0, <ce66352d3eb21825410af8b91db7cc4bb8e22c98, 427faee167bce4ccb0b22f6815a9ac509e31d4c3, 6.6.158, <=6.6.*, <5.15, <1dd562f3019019ffdf4b396570613053facda9ee, 5.15, <=6.18.*, <=7.2.*, <=*, <1d56a00ec91f2885c64ea5b8cea18cb746b91bbb, <e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc, 6.12.111, 7.3

Description

In the Linux kernel, the following vulnerability has been resolved: net: ipv6: Fix UDP length overflow with PMTU discover and big MTU This commit bounds cork->base.fragsize to IP6_MAX_MTU for UDP sockets to avoid a possible overflow of UDP length that triggers a WARN in udp_set_len_short when setsockopt IPV6_MTU_DISCOVER is set to IPV6_PMTUDISC_DO or IPV6_PMTUDISC_PROBE, and a large packet is sent over a netdev with an unusually large MTU. Steps to reproduce (included in the new selftest): 1. Set device MTU bigger than IP6_MAX_MTU. cork->base.fragsize will be set to that MTU in ip6_setup_cork. 2. Set IPV6_MTU_DISCOVER to IPV6_PMTUDISC_PROBE or IPV6_PMTUDISC_DO. It lets maxnonfragsize be set to device MTU (cork->fragsize) in __ip6_append_data, rather than to IP6_MAX_MTU. 3. Send 65528 bytes of payload (+8 bytes of UDP header, +40 bytes of IPv6 header). Device MTU allows it (it's only one byte bigger than IP6_MAX_MTU, and the device MTU is bigger than that). 4. The UDP length in the built packet is 65536, which overflows the 16-bit length field and triggers the WARN in udp_set_len_short. To avoid breaking sending UDP jumbograms over raw IPv6 sockets, limit the change to UDP sockets only. The original overflow bug with IPv6 and IPV6_PMTUDISC_DO seems to predate git history (verified reproduction on 2.6.21), was fixed later, and then reappeared in commit 427faee167bc ("net: ipv6: introduce ip6_dst_mtu_maybe_forward"), which is chosen as the Fixes tag here. The overflow with IPV6_PMTUDISC_PROBE reproduces since its introduction in commit 628a5c561890 ("[INET]: Add IP(V6)_PMTUDISC_RPOBE").

Gravité et risque d'exploitation

CVE-2026-97984 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 0.17 %, ce qui la place devant 5.6 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.12.*, 7.2.7, <0ae10b6be49b425827659b23bcce498f80eb7182, 6.18.53, 0, <ce66352d3eb21825410af8b91db7cc4bb8e22c98, 427faee167bce4ccb0b22f6815a9ac509e31d4c3, 6.6.158, <=6.6.*, <5.15, <1dd562f3019019ffdf4b396570613053facda9ee, 5.15, <=6.18.*, <=7.2.*, <=*, <1d56a00ec91f2885c64ea5b8cea18cb746b91bbb, <e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc, 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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