{"id":"CVE-2026-74586","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-74586","summary":"sctp: clear new_transport when removing a peer","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: clear new_transport when removing a peer\n\nsctp_process_asconf_param() stores a newly added peer transport in\nasoc->new_transport. After all parameters in the ASCONF chunk have been\nprocessed, sctp_sf_do_asconf() uses this pointer to send a HEARTBEAT to the\nnew transport.\n\nAn authenticated ASCONF from a remote SCTP peer can add a transport and\nremove it again with a wildcard DEL-IP parameter in the same chunk. The\nwildcard deletion preserves the transport on which the ASCONF arrived, but\nremoves the newly added transport through\nsctp_assoc_del_nonprimary_peers(). The removal does not clear\nasoc->new_transport, leaving it pointing to the removed transport.\n\nsctp_sf_do_asconf() then creates a HEARTBEAT whose chunk->transport points\nto the removed transport without holding a transport reference. During\nlocal address replacement, src_out_of_asoc_ok keeps this HEARTBEAT on\ncontrol_chunk_list. After the transport is freed by RCU, a successful\nASCONF_ACK for the replacement address releases the queued HEARTBEAT and\nsctp_outq_select_transport() reads the freed transport's state.\n\nThe issue was found during a static audit of SCTP objects. With an\nauthenticated peer, the reproducer triggered the same KASAN report in 2\nof 2 unpatched runs on a KASAN-enabled netdev/main kernel:\n\n  BUG: KASAN: slab-use-after-free in sctp_outq_select_transport\n  Read of size 4 at addr ffff88800b9bd95c by task python3/197\n\n  Call Trace:\n   sctp_outq_select_transport+0x549/0x8b0 [sctp]\n   sctp_outq_flush+0x306/0x2c60 [sctp]\n   sctp_transport_immediate_rtx+0xaf/0x260 [sctp]\n   sctp_process_asconf_ack+0xa48/0xf70 [sctp]\n\n  Allocated by task 197:\n   sctp_transport_new+0x68/0x650 [sctp]\n   sctp_assoc_add_peer+0x258/0x12a0 [sctp]\n   sctp_process_asconf+0x5e9/0x1090 [sctp]\n\n  Last potentially related work creation:\n   __call_rcu_common.constprop.0+0x77/0xb70\n   sctp_assoc_del_nonprimary_peers+0x7c/0xd0 [sctp]\n   sctp_process_asconf+0xd9c/0x1090 [sctp]\n\nThe first invalid access was a four-byte read of transport->state at\nnet/sctp/outqueue.c:833. The same reproducer completed the full\nauthenticated ASCONF and local-address replacement sequence with this\nchange without a KASAN report or oops.\n\nClear new_transport when its peer is removed, before it can be used to\ncreate the HEARTBEAT.","published":"2026-08-22T15:31:39.094Z","modified":"2026-08-24T11:46:38.912346575Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"5.10.265"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/163847552a571bd55094291f4ffcdc1de0f14a7b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/291accf36febce751021888de5f15090f4875b56"},{"type":"WEB","url":"https://git.kernel.org/stable/c/31efa656cf6aface26e88f038c14f22ee6ca1500"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3b539b317cd052236fed0350364ff1268996ba46"},{"type":"WEB","url":"https://git.kernel.org/stable/c/beb33f8ee1ca83acddb2a5ae80f3d22ec550b4c3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c0f973bb5118dd1b146cda3fcc8af6f6057befec"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ca33df36aa0143a1d04f57d2086020c12e7eddb7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/db9d8e3b670f841755bc2018f178472dc6064d27"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74586.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74586"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-24T11:46:38.912346575Z"}}