CVE-2026-98323: RDMA/siw: Bound fragmented header copies by the remaining length

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-06 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/siw: Bound fragmented header copies by the remaining length 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.

Affected products

Linux kernel: from 5.10.150 before 5.10.271; from 5.15.75 before 5.15.222; from 5.4.220 before 5.5; from 5.19.17 before 5.20; from 6.0.3 before 6.1; 6.1 — fixed in 5.10.271, 5.15.222, 5.20, 5.5, 6.1, 7.3

How to fix

Upgrade to a fixed version: Linux kernel 5.10.271, 5.15.222, 5.20, 5.5. Check the vendor advisory for mitigations.

References

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