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CVE-2026-98323
RDMA/siw: Bound fragmented header copies by the remaining length
Published 2026-10-06 (13 days ago) by the Linux kernel CNA. Subsystem drivers/infiniband. Debian urgency: not yet assigned.
Debian does not build this code. The per-release build detail is under "Where it lives" below.
What to do, per Debian release
Debian's own status for CVE-2026-98323 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-6568-1 · 2026-10-16 · text | 6.12.113-1 | Update the kernel and reboot. DSA-6568-1 shipped the fix on 2026-10-16, in 6.12.113-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.8-1 | Update the kernel and reboot. Fixed in 7.2.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.8-1 | Update the kernel and reboot. Fixed in 7.2.8-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
siw_get_hdr() can receive an extended DDP/RDMAP header across more than one TCP callback. The first callback may receive most of the header, while the next one still limits the copy to hdrlen - MIN_DDP_HDR instead of the number of missing bytes. This makes the destination move past the end of the header and overwrite the receive state, including fpdu_part_rcvd. A later callback can then use a negative fpdu_part_rcvd value as a copy offset, which creates an OOB write. Use the number of header bytes already received when calculating the next copy length.
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/infiniband/sw/siw/siw_qp_rx.c
- What this is
- SOFT-IWARP DRIVER (siw)MAINTAINERS section matched on drivers/infiniband/sw/siw/ · linux-rdma@vger.kernel.org · Supported
- Kernel module
- none to look for. The file would have gone into siw, and Debian does not compile it into that module, so finding siw in lsmod would say nothing about this CVE.
Check it on the machine
grep -wE 'CONFIG_INFINIBAND|CONFIG_RDMA_SIW' /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.
Show whether Debian builds this, per release
Debian does not build this code. In 4 releases below, every kernel flavour Debian publishes has the switch off, so the vulnerable file is compiled into no kernel binary Debian ships.
- bookworm, trixie, forky, sidn
- n
- not enabled on any flavour - this release does not build the code
- Build switches
- CONFIG_INFINIBAND, CONFIG_RDMA_SIW
- Reads as
- all on means the file is compiled; any one off means it is not.
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
- 2026-10-06 (13 days 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
- 0.56%, higher than 45.4% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/infiniband
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.10.150 | 5.10.271 | 2c6fbcf4bfac |
| 5.15.75 | 5.15.222 | af9f5b474a26 |
| 6.1 | 6.1.189 | 262dcd809723 |
| 6.1 | 6.6.158 | eb4d7a946970 |
| 6.1 | 6.12.112 | 8628f8ebf416 |
| 6.1 | 6.18.54 | b72dcfb9bf1f |
| 6.1 | 7.2.8 | e6bdfdf3bcb0 |
| 6.1 | 7.3 | 9ff797e516db |
| 5.4.220 | 0 | 0 |
| 5.19.17 | 0 | 0 |
| 6.0.3 | 0 | 0 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DSA-6568-1 | 2026-10-16 | trixie 6.12.113-1 | 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
- The malformed input is the remote iWARP peer's own MPA/DDP/RDMAP header bytes on the siw TCP connection. The peer splits an extended header (e.g. RDMA Read Request, 44 bytes) across TCP segments, and siw_qp_llp_data_ready() -> tcp_read_sock() -> siw_tcp_rx_data() -> siw_get_hdr() parses them. The transport is routable TCP.
- AC:LAttack complexity, low
- The peer fully controls TCP segmentation, so it can deterministically end a segment with fpdu_part_rcvd between 16 and hdrlen. The next segment then copies hdrlen-16 bytes at that offset. No race or state outside the attacker's control is involved beyond siw serving an iWARP listener.
- PR:NPrivileges required, none
- Once the MPA exchange puts the QP in RTS, siw_get_hdr() parses every incoming FPDU header, and neither MPA nor DDP authenticates the peer. ULP authorisation (such as an nvmet-rdma host NQN check) only arrives in messages parsed by this same path, so the overflow fires before any credential check.
- UI:NUser interaction, none
- No victim action is needed. The attacker connects to the iWARP service and sends crafted fragmented FPDUs, and siw processes them in its sk_data_ready callback.
- S:UScope, unchanged
- The corruption is confined to kernel memory of the host running siw (struct siw_qp and its neighbours). That is the same security authority as the vulnerable component, with no VM or IOMMU boundary crossed.
- C:HConfidentiality impact, high
- The overflow writes peer bytes over siw_rx_stream fields after hdr, including fpdu_part_rcvd. A negative fpdu_part_rcvd then makes skb_copy_bits() write to c_hdr plus an attacker-chosen offset. A controlled kernel write like this can be turned into arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- siw_get_hdr() copies up to hdrlen-17 attacker bytes past srx->hdr (27 for rreq), overwriting the receive state. The next callback uses the corrupted negative fpdu_part_rcvd as the destination offset of skb_copy_bits(), giving an out-of-bounds kernel write whose offset and data are attacker-controlled.
- A:HAvailability impact, high
- Corrupting fpdu_part_rcvd/fpdu_part_rem and writing out of bounds from siw_qp crashes or panics the kernel. A remote peer can repeat this on every connection.