{"id":"DEBIAN-CVE-2026-74586","details":"In the Linux kernel, the following vulnerability has been resolved:  sctp: clear new_transport when removing a peer  sctp_process_asconf_param() stores a newly added peer transport in asoc-\u003enew_transport. After all parameters in the ASCONF chunk have been processed, sctp_sf_do_asconf() uses this pointer to send a HEARTBEAT to the new transport.  An authenticated ASCONF from a remote SCTP peer can add a transport and remove it again with a wildcard DEL-IP parameter in the same chunk. The wildcard deletion preserves the transport on which the ASCONF arrived, but removes the newly added transport through sctp_assoc_del_nonprimary_peers(). The removal does not clear asoc-\u003enew_transport, leaving it pointing to the removed transport.  sctp_sf_do_asconf() then creates a HEARTBEAT whose chunk-\u003etransport points to the removed transport without holding a transport reference. During local address replacement, src_out_of_asoc_ok keeps this HEARTBEAT on control_chunk_list. After the transport is freed by RCU, a successful ASCONF_ACK for the replacement address releases the queued HEARTBEAT and sctp_outq_select_transport() reads the freed transport's state.  The issue was found during a static audit of SCTP objects. With an authenticated peer, the reproducer triggered the same KASAN report in 2 of 2 unpatched runs on a KASAN-enabled netdev/main kernel:    BUG: KASAN: slab-use-after-free in sctp_outq_select_transport   Read of size 4 at addr ffff88800b9bd95c by task python3/197    Call Trace:    sctp_outq_select_transport+0x549/0x8b0 [sctp]    sctp_outq_flush+0x306/0x2c60 [sctp]    sctp_transport_immediate_rtx+0xaf/0x260 [sctp]    sctp_process_asconf_ack+0xa48/0xf70 [sctp]    Allocated by task 197:    sctp_transport_new+0x68/0x650 [sctp]    sctp_assoc_add_peer+0x258/0x12a0 [sctp]    sctp_process_asconf+0x5e9/0x1090 [sctp]    Last potentially related work creation:    __call_rcu_common.constprop.0+0x77/0xb70    sctp_assoc_del_nonprimary_peers+0x7c/0xd0 [sctp]    sctp_process_asconf+0xd9c/0x1090 [sctp]  The first invalid access was a four-byte read of transport-\u003estate at net/sctp/outqueue.c:833. The same reproducer completed the full authenticated ASCONF and local-address replacement sequence with this change without a KASAN report or oops.  Clear new_transport when its peer is removed, before it can be used to create the HEARTBEAT.","modified":"2026-09-19T22:02:34.335629099Z","published":"2026-08-22T16:16:30.687Z","upstream":["CVE-2026-74586"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-74586"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.187-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.128-1","6.1.129-1","6.1.133-1","6.1.135-1","6.1.137-1","6.1.139-1","6.1.140-1","6.1.147-1","6.1.148-1","6.1.153-1","6.1.158-1","6.1.159-1","6.1.162-1","6.1.164-1","6.1.170-1","6.1.170-2","6.1.170-3","6.1.172-1","6.1.174-1","6.1.176-1","6.1.177-1","6.1.180-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not 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