CVE-2026-43186

Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data() On the receive path, __ioam6_fill_trace_data() uses trace->nodelen to decide how much data to write for each node. It trusts this field as-is from the incoming packet, with no consistency check against trace->type (the 24-bit field that tells which data items are present). A crafted packet can set nodelen=0 while setting type bits 0-21, causing the function to write ~100 bytes past the allocated region (into skb_shared_info), which corrupts adjacent heap memory and leads to a kernel panic. Add a shared helper ioam6_trace_compute_nodelen() in ioam6.c to derive the expected nodelen from the type field, and use it: - in ioam6_iptunnel.c (send path, existing validation) to replace the open-coded computation; - in exthdrs.c (receive path, ipv6_hop_ioam) to drop packets whose nodelen is inconsistent with the type field, before any data is written. Per RFC 9197, bits 12-21 are each short (4-octet) fields, so they are included in IOAM6_MASK_SHORT_FIELDS (changed from 0xff100000 to 0xff1ffc00).

Gravité et risque d'exploitation

CVE-2026-43186 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 0.86 %, ce qui la place devant 57.9 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <e90346a2f1e8917d5760a44a1f61c44e3b36d96b, <=6.1.*, <=6.12.*, 0, 7.0, <6db8b56eed62baacaf37486e83378a72635c04cc, <632d233cf2e64a46865ae2c064ae3c9df7c8864f, 6.12.75, 6.1.165, <=6.6.*, <=6.19.*, <f4d9d4b8fd839719d564651671e24c62c545c23b, <5.15, <0591d6509c2ff13f09ea2998434aba0c0472e978, <fb3c662fafebc5b9d74417ed1de8759f6bb72143, 5.15, <=6.18.*, 9ee11f0fff205b4b3df9750bff5e94f97c71b6a0, 6.19.6, 6.6.128, 6.18.16, <=*, <=5.15.*, <ea3632aefc04205436868541638e26f4a74d5637, 5.15.202) 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

• https://git.kernel.org/stable/c/f4d9d4b8fd839719d564651671e24c62c545c23b
• https://git.kernel.org/stable/c/fb3c662fafebc5b9d74417ed1de8759f6bb72143
• https://git.kernel.org/stable/c/632d233cf2e64a46865ae2c064ae3c9df7c8864f
• https://git.kernel.org/stable/c/0591d6509c2ff13f09ea2998434aba0c0472e978
• https://git.kernel.org/stable/c/e90346a2f1e8917d5760a44a1f61c44e3b36d96b
• https://git.kernel.org/stable/c/ea3632aefc04205436868541638e26f4a74d5637
• https://git.kernel.org/stable/c/6db8b56eed62baacaf37486e83378a72635c04cc