CVE-2026-89969

Description

In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU nvmet_tcp_try_recv_pdu() reads a PDU header into the fixed 128-byte queue->pdu union, then computes the remaining payload length as queue->left = hdr->hlen - queue->offset + hdgst; and reads that many more bytes into &queue->pdu + queue->offset, without ever bounding the result against sizeof(queue->pdu). A struct nvme_tcp_icreq_pdu is itself 128 bytes, exactly the size of the union. Once a header digest has been negotiated (hdgst = 4), a second ICReq passes the hlen == nvmet_tcp_pdu_size() check but yields queue->left = 128 - 8 + 4 = 124, so bytes 8..132 are written into the 128-byte buffer -- 4 bytes past its end, over queue->hdr_digest and queue->data_digest. Those bytes are attacker-controlled (an ICReq carries no digest), and the duplicate ICReq is only rejected later, after the overflow. A remote unauthenticated host can thus corrupt kernel memory adjacent to the receive buffer. Reject any PDU whose declared length would read past the end of queue->pdu before the second recv.

Gravité et risque d'exploitation

CVE-2026-89969 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 0.71 %, ce qui la place devant 52.8 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <=6.12.*, 5.15.221, 5.10.270, 0, <dbc4acbdb3ca8c81441368ad7409b8f77d4de8f6, <14cc5a7e77731497d5bea70f3bb05df7eda982e4, 6.1.188, 6.18.51, <58dc6035b79c4c73c0cbf9ec9f68a7f117b2b3e6, <a3f0bcfbaf3312a5754d1ce020a07d394669eb25, 872d26a391da92ed8f0c0f5cb5fef428067b7f30, <=5.10.*, <=6.6.*, 5.0, 7.2.5, 6.6.157, <5.0, <=6.18.*, 6.12.110, <=7.2.*, <=*, <=5.15.*, <4f84d42c53c49557fb1ef285c683b0a81b576c74, <d95d342bc0ea82dc79e6362b2f1f997431750e4c, <3a385e0c39efbe34db8edd95900c123113ae3450, <cf5f39d2b58f97e0cd1829c4a6aeef17f1607cca, 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

• https://git.kernel.org/stable/c/a3f0bcfbaf3312a5754d1ce020a07d394669eb25
• https://git.kernel.org/stable/c/4f84d42c53c49557fb1ef285c683b0a81b576c74
• https://git.kernel.org/stable/c/58dc6035b79c4c73c0cbf9ec9f68a7f117b2b3e6
• https://git.kernel.org/stable/c/cf5f39d2b58f97e0cd1829c4a6aeef17f1607cca
• https://git.kernel.org/stable/c/3a385e0c39efbe34db8edd95900c123113ae3450
• https://git.kernel.org/stable/c/dbc4acbdb3ca8c81441368ad7409b8f77d4de8f6
• https://git.kernel.org/stable/c/d95d342bc0ea82dc79e6362b2f1f997431750e4c
• https://git.kernel.org/stable/c/14cc5a7e77731497d5bea70f3bb05df7eda982e4