CVE-2026-74430

Technical Description

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

rxrpc: Fix ACKALL packet handling

rxrpc_input_ackall() accepts ACKALL packets without checking whether the

call is in a state that can legitimately have outstanding transmit buffers.

A forged ACKALL can therefore reach a new service call in

RXRPC_CALL_SERVER_RECV_REQUEST before any reply packets have been queued.

In that state call->tx_top is zero and call->tx_queue is NULL, so

rxrpc_rotate_tx_window() dereferences a NULL txqueue and triggers a

null-pointer dereference.

Fix the handling of ACKALL packets by the following means:

(1) Add two new call states: RXRPC_CALL_CLIENT_PRE_SEND which indicates

that the client call is connected, but nothing has been transmitted as

yet; and RXRPC_CALL_CLIENT_AWAIT_ACK, which indicates that everything

has been transmitted at least once, but we're now waiting for the

stuff remaining in the Tx buffer to be ACK'd (retransmissions may

still happen).

T

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References