CVE-2026-64564

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> sctp: don&amp;#39;t free the ASCONF&amp;#39;s own transport in DEL-IP processing<br /> <br /> sctp_process_asconf() caches the transport the ASCONF chunk is processed<br /> against in asconf-&gt;transport (== chunk-&gt;transport, set once in sctp_rcv()).<br /> For an ASCONF located through its Address Parameter by<br /> __sctp_rcv_asconf_lookup(), that cached transport corresponds to the<br /> Address Parameter, which need not be the packet&amp;#39;s source address.<br /> <br /> sctp_process_asconf_param() rejects a DEL-IP for the packet source address<br /> (ADDIP D8, SCTP_ERROR_DEL_SRC_IP), but nothing protects asconf-&gt;transport.<br /> A single ASCONF can therefore carry, in order:<br /> <br /> [Address Parameter L] [DEL-IP L] [DEL-IP 0.0.0.0]<br /> <br /> where L differs from the source. The DEL-IP for L passes the D8 check and<br /> calls sctp_assoc_rm_peer() on the transport that asconf-&gt;transport still<br /> points at, freeing it (RCU-deferred). The following wildcard DEL-IP then<br /> reuses the now-dangling asconf-&gt;transport in sctp_assoc_set_primary() and<br /> sctp_assoc_del_nonprimary_peers(): set_primary() dereferences the freed<br /> transport (-&gt;ipaddr, -&gt;state) and plants the dangling pointer into<br /> asoc-&gt;peer.primary_path / active_path, and del_nonprimary_peers(), keeping<br /> only the pointer that is no longer on the list, removes every real<br /> transport, leaving the association with a transport_count of 0 and<br /> primary_path/active_path pointing at freed memory.<br /> <br /> Reject a DEL-IP that targets the transport the ASCONF is being processed<br /> against, mirroring the existing source-address guard, so the wildcard<br /> branch can never reuse a freed transport.