Linux Linux Kernel Vulnerability Rated 8.8 CVSS

Status: UPDATED  |  Advisory ID: CVE-2026-72380

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

xen/pvcalls: bound backend response req_id before indexing rsp[]

pvcalls_front_event_handler() takes req_id directly from the

backend-supplied ring response and uses it to index the fixed-size

bedata->rsp[] array for a memcpy() and a store, with no range check. A

malicious or buggy backend can set req_id past PVCALLS_NR_RSP_PER_RING

and drive an out-of-bounds write past the bedata allocation.

req_id was also declared int while the wire field rsp->req_id is u32, so

a range check on the signed value alone is insufficient: a backend

req_id of 0xffffffff becomes -1, passes a >= PVCALLS_NR_RSP_PER_RING

test and indexes bedata->rsp[-1]. Declare req_id as u32 so a single

bound covers both ends.

A backend that sends an out-of-range req_id has violated the wire

protocol, so rather than silently dropping the response, log once and

stop trusting the backend: set bedata->disabled. The event handler then

ignores further responses, and the request paths that wait for a

response return -EIO instead of blocking forever. This mirrors the

fatal-error handling xen-netback uses (xenvif_fatal_tx_err()).

The pvcalls frontend currently trusts its backend, so this is not a

classic-Xen security issue, but it matters for hardening PV frontends

against malicious backends (confidential and disaggregated deployments). (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References