CVE-2026-74742

A flaw was found in the Linux kernel's veth component. In a multi-queue setup without an eXpress Data Path (XDP) program attached, the veth_poll() function incorrectly derives the index of the peer transmit (TX) queue to wake. This can cause a TX queue to stop indefinitely if it becomes full, as the polling mechanism fails to reactivate it. This issue leads to a Denial of Service (DoS) condition, preventing further network traffic processing on the affected queue.

A MODERATE severity denial-of-service flaw was found in the Linux kernel's veth (virtual Ethernet) driver, which provides the virtual network links used for container and network-namespace networking. In a multi-queue veth setup with GRO enabled and no XDP program attached, veth_poll() derives the peer transmit queue index to wake from rq->xdp_rxq.queue_index, a field that is only initialized when an XDP program is attached; on the plain GRO/NAPI path it stays 0 for every queue. When veth_xmit() stops a non-zero peer TX queue because its ptr_ring is full, the poller therefore wakes queue 0 instead, and because veth implements no ndo_tx_timeout the netdev watchdog does not intervene either, so the stopped queue is never woken again and traffic on that queue stalls indefinitely. Exploiting this requires a local attacker or workload able to push enough traffic through an affected multi-queue veth pair to fill the ptr_ring, which is why Red Hat rates the flaw MODERATE (CVSS 5.5, AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) rather than the network-vector CVSS 7.5 score assigned in the upstream CVE record. The vulnerable code is not present in the shipped kernels of Red Hat Enterprise Linux 7, 8, 9, and 10 or Red Hat In-Vehicle OS, so these products are not affected; the Red Hat Enterprise Linux 6 Extended Lifecycle 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.