# CVE-2026-74430: linux: In the Linux kernel, the following vulnerability has been resolved:  rxrpc: Fix ACKALL packet handling  rxrpc_input_a...

CVE-2026-74430 is fixed in linux on 1 platform by DEBIAN-CVE-2026-74430 (version 7.1.5-1), released August 15, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-74430
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0061
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 15, 2026

## 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).       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.       RXRPC_CALL_CLIENT_AWAIT_REPLY is then narrowed in scope to indicate      that all Tx packets have been ACK'd and we're now waiting for the      reply to be received.   (2) As per Wyatt Feng's original patch[1], the ACKALL handler then checks      that the call state is one in which there might be stuff in the Tx      buffer to ACK, but now this includes AWAIT_ACK rather than      AWAIT_REPLY.  ACKALL packets are ignored if received in the wrong      state.       Note that unlike Wyatt Feng's patch, it's no longer necessary to check      to see if the Tx buffer exists as this the state set now covers this.   (3) Make the ACKALL handler use call->tx_transmitted rather than      call->tx_top as the former is explicitly the highest packet seq number      transmitted, whereas the latter has a looser definition.  Thanks to Jeffrey Altman for a description of the history of the ACKALL packet[1].

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.1.5-1 | [DEBIAN-CVE-2026-74430](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74430.md) | Aug 15, 2026 |

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Data as of 2026-11-09T07:25:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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