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CVE-2026-43501

Vulnérabilité critique dans Linux (Linux)

CVSS 9.8 · Critique
EPSS 1.0%
Linux•Linux•Versions : <bde199c72d319a4e207f88daabc888317504e2fb, 7.0.4, <=6.1.*, <=7.0.*, <=6.12.*, 0, 6.18.27, <9e6bf146b55999a095bb14f73a843942456d1adc, <8e8be63465a5e80394c70324603dfea1bfdad48f, <5.7, 5.15.209, <c261d07a80576dc8ccf394ef8f074f8c67a06b37, <=5.10.*, <=6.6.*, 6.1.175, 7.1, <=6.18.*, 5.10.258, 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3, 5.7, <=*, <be1fa0aa9b4fdd5a8b7a61ba520a690a68391e6e, <=5.15.*, <4babc2d9fda2df43823b85d08a0180b68f1b0854, <0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402, 6.6.140, <7398ebefbfd4f8a31d4f665a4213302fa995494b, 6.12.86

Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: rpl: reserve mac_len headroom when recompressed SRH grows ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->daddr, recompresses, then pulls the old header and pushes the new one plus the IPv6 header back. The recompressed header can be larger than the received one when the swap reduces the common-prefix length the segments share with daddr (CmprI=0, CmprE>0, seg[0][0] != daddr[0] gives the maximum +8 bytes). pskb_expand_head() was gated on segments_left == 0, so on earlier segments the push consumed unchecked headroom. Once skb_push() leaves fewer than skb->mac_len bytes in front of data, skb_mac_header_rebuild()'s call to: skb_set_mac_header(skb, -skb->mac_len); will store (data - head) - mac_len into the u16 mac_header field, which wraps to ~65530, and the following memmove() writes mac_len bytes ~64KiB past skb->head. A single AF_INET6/SOCK_RAW/IPV6_HDRINCL packet over lo with a two segment type-3 SRH (CmprI=0, CmprE=15) reaches headroom 8 after one pass; KASAN reports a 14-byte OOB write in ipv6_rthdr_rcv. Fix this by expanding the head whenever the remaining room is less than the push size plus mac_len, and request that much extra so the rebuilt MAC header fits afterwards.

Gravité et risque d'exploitation

CVE-2026-43501 obtient un score CVSS de 9.8/10, soit une gravité critique. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.99 %, ce qui la place devant 61.9 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <bde199c72d319a4e207f88daabc888317504e2fb, 7.0.4, <=6.1.*, <=7.0.*, <=6.12.*, 0, 6.18.27, <9e6bf146b55999a095bb14f73a843942456d1adc, <8e8be63465a5e80394c70324603dfea1bfdad48f, <5.7, 5.15.209, <c261d07a80576dc8ccf394ef8f074f8c67a06b37, <=5.10.*, <=6.6.*, 6.1.175, 7.1, <=6.18.*, 5.10.258, 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3, 5.7, <=*, <be1fa0aa9b4fdd5a8b7a61ba520a690a68391e6e, <=5.15.*, <4babc2d9fda2df43823b85d08a0180b68f1b0854, <0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402, 6.6.140, <7398ebefbfd4f8a31d4f665a4213302fa995494b, 6.12.86) 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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