High [CVE-2026-74430] Fix ACKALL packet handling
This high-severity Red Hat Linux advisory covers CVE-2026-74430 affecting Red Hat Enterprise Linux 10, Red Hat package: kernel.
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Summary
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).
The RXRPC_CALL_CLIENT_PRE_SEND state is set when the call is assigned a channel and transitions to RXRPC_CALL_CLIENT_SEND_REQUEST when the first packet is transmitted.
Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat package: kernel.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 14 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 14 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 14 days ago·verify at source
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