Critical severity · published Sep 16, 2026
CVE-2026-89969
nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU
9.8
CVSS
0.7%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 53% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
Linux · Linux
872d26a391da92ed8f0c0f5cb5fef428067b7f30 before a3f0bcfbaf3312a5754d1ce020a07d394669eb25; 872d26a391da92ed8f0c0f5cb5fef428067b7f30 before 4f84d42c53c49557fb1ef285c683b0a81b576c74; 872d26a391da92ed8f0c0f5cb5fef428067b7f30 before 58dc6035b79c4c73c0cbf9ec9f68a7f117b2b3e6; 872d26a391da92ed8f0c0f5cb5fef428067b7f30 before cf5f39d2b58f97e0cd1829c4a6aeef17f1607cca; 872d26a391da92ed8f0c0f5cb5fef428067b7f30 before 3a385e0c39efbe34db8edd95900c123113ae3450; 872d26a391da92ed8f0c0f5cb5fef428067b7f30 before dbc4acbdb3ca8c81441368ad7409b8f77d4de8f6; +3 more · source: vendor