CVE-2026-74627

A flaw was found in the Linux kernel's net: devmem component. This vulnerability occurs when net_iov and page-backed fragments are improperly mixed within a single skb (socket buffer) in the zerocopy_fill_skb_from_devmem() function. This improper handling can lead to a system crash, resulting in a Denial of Service (DoS).

A flaw of MODERATE impact was found in the Linux kernel's net devmem (device memory TCP) zero-copy transmit path. In zerocopy_fill_skb_from_devmem(), net_iov-backed and page-backed fragments could be mixed within a single socket buffer (skb), violating the invariant that an skb must use only one kind of fragment backing. A local process able to use the devmem TX zero-copy send interface could construct such a mixed skb, causing lower network stack code to mis-handle the fragment backing type and crash the kernel, resulting in a denial of service. Red Hat rates this flaw MODERATE (CVSS 5.5, AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) because reliable triggering requires local access to the devmem TX interface and only availability impact (kernel crash) has been established, with no demonstrated impact on confidentiality or integrity; this differs from the upstream CVSS 7.8 (IMPORTANT) rating, which assumes full confidentiality, integrity, and availability impact. The vulnerable code was introduced upstream in Linux kernel version 6.16 and is not present in any in-scope Red Hat product version: all Red Hat Enterprise Linux 7 through 10 streams (kernel and kernel-rt) and Red Hat In-Vehicle OS versions are listed as not affected for this reason, and the Red Hat Enterprise Linux 6 Extended Life Cycle Support stream is out of support scope.

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.