CVE-2026-74434
Vulnérabilité critique dans Linux (Linux)
Description
In the Linux kernel, the following vulnerability has been resolved: rxrpc: Don't move a peeked OOB message onto the pending queue rxrpc_recvmsg_oob() takes a received oob message off recvmsg_oobq and, if a response is needed, moves it onto the pending_oobq tree. However, only the unlink from recvmsg_oobq is guarded by MSG_PEEK; the move onto pending_oobq always runs. As a result, reading a challenge with MSG_PEEK leaves the skb on recvmsg_oobq while also adding it to pending_oobq. Since struct sk_buff's rbnode shares storage with its next and prev pointers, rb_insert_color() overwrites the list linkage, and the skb, which holds a single reference, becomes reachable from both queues at once. When the socket is closed both queues are drained in turn. While draining recvmsg_oobq, __skb_unlink() follows the next and prev pointers that rbnode has overwritten and writes to a bad address. Also, as the skb holds a single reference but is freed from each queue, both the skb and the connection reference it holds are released twice. This leads to memory corruption and to a use-after-free caused by the connection refcount underflow. MSG_PEEK does not consume the message from the queue, so only unlink it from recvmsg_oobq and then move it onto pending_oobq or free it when the message is actually consumed.
Gravité et risque d'exploitation
CVE-2026-74434 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 0.63 %, ce qui la place devant 49.3 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions <6.16, 7.1.5, 5800b1cf3fd8ccab752a101865be1e76dac33142, 6.18.40, <=*, 6.16, <5f470cc883416fea6d3bce18ef96bf91dd49ffc3, <=6.18.*, <=7.1.*, <5801cff7d5d7b4e9d877dfb627b23eb63167f02c, 0, 7.2, <9ada3931beb37068fcb725b34b0398457009f343) 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.