CVE-2026-98323

A flaw was found in the Linux kernel's Software iWARP (siw) Remote Direct Memory Access (RDMA) driver. When handling extended protocol headers split across multiple network packets, the driver incorrectly calculates the remaining length during the copy operation, leading to an out-of-bounds memory write. A remote attacker could exploit this vulnerability by sending fragmented network traffic, potentially resulting in memory corruption and a Denial of Service (DoS).

An out-of-bounds memory write flaw rated Important by Red Hat affects the Linux kernel's Software iWARP (siw) RDMA driver in Red Hat Enterprise Linux 8 and 9 (kernel and kernel-rt packages) and in the RHEL CoreOS 9-based nodes shipped with OpenShift Container Platform 4. The flaw is in siw_get_hdr(), which can receive an extended DDP/RDMAP header across more than one TCP callback. After a first callback receives most of the header, the next callback still limits its copy to hdrlen - MIN_DDP_HDR instead of the number of bytes still missing, so the copy destination moves past the end of the header and overwrites the receive state, including fpdu_part_rcvd. A later callback can then use a negative fpdu_part_rcvd value as a copy offset, producing an out-of-bounds write. A remote attacker able to deliver deliberately fragmented TCP traffic to a host with an exposed siw/iWARP endpoint could exploit this flaw to corrupt kernel memory, most likely crashing the system and causing a denial of service. Fixes for the affected Red Hat Enterprise Linux and OpenShift Container Platform streams are being pursued. Red Hat rates this flaw Important (CVSS 3.1 base score 7.0), while the upstream CVE record assigns a Critical 9.8 score; the difference reflects Red Hat's assessment of the exploitability and realistic impact of this flaw in supported products. Red Hat Enterprise Linux 6, 7, 8.4, and 8.6, Red Hat Enterprise Linux 10, and Red Hat In-Vehicle OS are not affected because the vulnerable code is not present in those streams.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.