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CVE-2025-38264
nvme-tcp: sanitize request list handling
Published 2025-07-09 (15 months 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-2025-38264 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 | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixed | 6.12.37-1 | Update the kernel and reboot. Fixed in 6.12.37-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 6.12.37-1 | Update the kernel and reboot. Fixed in 6.12.37-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.12.37-1 | Update the kernel and reboot. Fixed in 6.12.37-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Validate the request in nvme_tcp_handle_r2t() to ensure it's not part of any list, otherwise a malicious R2T PDU might inject a loop in request list processing.
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, sidm
- 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
- 2025-07-09 (15 months ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.33%, higher than 24.7% 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 | 6.12.36 | 78a4adcd3fed |
| 5.0 | 6.15.5 | f054ea625981 |
| 5.0 | 6.16 | 0bf04c874fcb |
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
- The vulnerable code is the NVMe-over-TCP host driver's PDU receive path, parsing an R2T PDU sent by a remote NVMe-oF target over TCP (port 4420); the malicious input arrives purely over the network from a compromised/rogue target or an on-path attacker.
- AC:LAttack complexity, low
- The target fully controls PDU content and timing — placing two R2T PDUs for the same command_id in a single TCP segment guarantees both are processed inside one nvme_tcp_recv_skb() pass with no send-path progress between them, creating the llist cycle deterministically with no race to win and no memory-layout dependency.
- PR:NPrivileges required, none
- NVMe/TCP requires no authentication by default (TLS and DH-HMAC-CHAP are optional, off in stock configs), so the remote peer needs zero privileges or credentials on the victim host — it simply answers I/O it is already being sent.
- UI:NUser interaction, none
- No victim action is required; once the host is connected to the target, ordinary filesystem/block I/O generates the in-flight commands and the malicious target triggers the bug on its own by replying with duplicate R2T PDUs.
- S:UScope, unchanged
- The corruption and the resulting hang are confined to the host kernel's own memory and scheduling authority; no VM, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- Beyond the list corruption, duplicate queueing lets the RX path reset req->state/offset/pdu_len while the TX path is consuming the request, desynchronizing req->iter so nvme_tcp_req_cur_page() reads past the bvec array and sock_sendmsg() splices unintended kernel pages directly to the attacker-controlled socket.
- I:HIntegrity impact, high
- Attacker-controlled input produces kernel linked-list pointer corruption (double llist_add plus repeated list_add of an already-linked entry into send_list) and lets an in-flight request's PDU header, ttag, and iterator state be rewritten mid-transfer, which is memory/state corruption leverageable for further control over kernel structures.
- A:HAvailability impact, high
- The injected cycle makes nvme_tcp_process_req_list() spin forever in the nvme_tcp_wq kworker while holding queue->send_mutex with no cond_resched(), producing a CPU soft lockup, RCU stalls, and a permanently wedged storage queue — a deterministic, unauthenticated remote kernel hang.