CVE-2026-89480

Public on 2026-09-11
Modified on 2026-09-15
Description
In the Linux kernel, the following vulnerability has been resolved:

nvme-tcp: reject a read that transferred too few bytes

nvme_tcp_recv_data() completes a request once the current C2HData PDU
has been consumed. Nothing compares the total bytes received against
the length the command asked for: struct nvme_tcp_request has no
receive-side counter, queue->data_remaining is per queue, and
blk_mq_end_request() completes for blk_rq_bytes(rq) unconditionally
with no residual concept anywhere above.

A controller can therefore answer a 4096-byte read with 512 bytes and
have it reported as a complete read; user space then gets 4096 bytes of
which 3584 are whatever was already in the page. I reproduced that with
a test target.

Count the bytes received and refuse to complete a successful read whose
count does not match, at the two NVME_TCP_F_DATA_SUCCESS paths and in
nvme_tcp_process_nvme_cqe(). The success test shifts req->status right
by one, because the driver keeps the wire value there and shifts it on
completion, so the check must see what the completion path will see.
Only REQ_OP_READ is checked, because there the length comes from the
sectors the request covers; a passthrough command is built by its
submitter, which picks both command and buffer, so the kernel has
nothing to compare against.
Severity
Medium severity
Medium
See what this means
CVSS v3 Base Score
4.8
See breakdown

Affected Packages

Platform Package Release Date Advisory Status
Amazon Linux 2 - Kernel-5.10 Extra kernel Pending Fix
Amazon Linux 2 - Kernel-5.15 Extra kernel Pending Fix
Amazon Linux 2 - Kernel-5.4 Extra kernel Pending Fix
Amazon Linux 2 - Core kernel Not Affected
Amazon Linux 2023 kernel Pending Fix
Amazon Linux 2023 kernel6.12 Pending Fix
Amazon Linux 2023 kernel6.18 Pending Fix
Amazon Linux 2027 Preview kernel7.1 Pending Fix

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 4.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N