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CVE-2026-89480
nvme-tcp: reject a read that transferred too few bytes
Published 2026-09-11 (37 days ago) by the Linux kernel CNA. Subsystem drivers/nvme. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-89480 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
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.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/nvme/host/tcp.c
- What this is
- NVM EXPRESS DRIVERMAINTAINERS section matched on drivers/nvme/host/ · linux-nvme@lists.infradead.org · Supported
- Kernel module
- nvme_tcp
Check it on the machine
grep -w CONFIG_NVME_TCP /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w nvme_tcpPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sid, bookworm · linux-6.12m
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switch
- CONFIG_NVME_TCP
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-09-11 (37 days ago)source
- CVSS
- 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:Nsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.41%, higher than 34.4% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/nvme
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.0 | 5.15.221 | a5c1bb0fb1ba |
| 5.0 | 6.1.188 | aa107e3a68f4 |
| 5.0 | 6.6.157 | fca3ebb63e5c |
| 5.0 | 6.12.109 | 99066cf9bba1 |
| 5.0 | 6.18.50 | 8a02ad98798f |
| 5.0 | 7.2.4 | 832a685efeb5 |
| 5.0 | 7.3 | 7fa3f73f6c8d |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- C2HData is parsed on the nvme-tcp host socket path (nvme_tcp_data_ready -> nvme_tcp_try_recv -> nvme_tcp_recv_skb -> nvme_tcp_recv_data) over routable TCP (typically 4420). A malicious or compromised NVMe-oF target, or an on-path injector into the default-unencrypted stream, triggers it from the network.
- AC:LAttack complexity, low
- nvme_tcp_handle_c2h_data() sets queue->data_remaining from the attacker-controlled PDU data_length with no comparison to req->data_len. A short or zero-length C2HData with NVME_TCP_F_DATA_SUCCESS, or a short C2HData plus a success CQE, completes the read every time; no race or layout dependence.
- PR:NPrivileges required, none
- The attacker is the NVMe-oF peer and needs no host account or capability. NVMe/TCP is unauthenticated by default (DH-HMAC-CHAP and TLS are optional), so a malicious, compromised, or spoofed target can short any in-flight read once the fabrics connection exists.
- UI:NUser interaction, none
- NVMe-oF controllers are persistent boot/autoconnect configuration and are re-established by nvme_tcp_error_recovery(). Namespace scan, partition probe, udev, and mounted-filesystem readahead issue REQ_OP_READ from kernel work without further victim action at attack time.
- S:UScope, unchanged
- Leftover host page-cache and buddy-page contents are exposed to local readers of the same kernel's NVMe device. No VM, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- blk_mq_end_request() completes the full blk_rq_bytes, so userspace and page cache see leftover destination-page bytes as valid data. Those pages are not zeroed; sibling CVE-2026-89481 showed they hold stale kernel data including struct page pointers. Leak size is attacker-chosen up to the whole I/O, including a 0-length SUCCESS PDU.
- I:NIntegrity impact, none
- The bug under-fills the bio and reports success; it does not write out of bounds, free an object, or give a kernel write/hijack primitive. Bytes the target does send are data a storage controller already controls, and leftover bytes are prior page contents rather than attacker-chosen writes.
- A:NAvailability impact, none
- The vulnerable path completes the request as success with no oops, panic, hang, deadlock, or leak. Availability of the host kernel is unaffected; error recovery (-EPROTO) exists only after the fix.