{"id":"CVE-2026-74586","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-74586","generatedAt":"2026-10-28T08:37:05.813Z","title":"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->new_transport.","description":"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":"2026-08-22T16:16:31.000Z","lastModified":"2026-10-16T20:17:41.000Z","status":"Received","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"cwe":[],"affected":[],"epss":{"score":0.005,"percentile":0.42613,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.50%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/163847552a571bd55094291f4ffcdc1de0f14a7b","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/291accf36febce751021888de5f15090f4875b56","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/31efa656cf6aface26e88f038c14f22ee6ca1500","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/3b539b317cd052236fed0350364ff1268996ba46","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/beb33f8ee1ca83acddb2a5ae80f3d22ec550b4c3","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c0f973bb5118dd1b146cda3fcc8af6f6057befec","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ca33df36aa0143a1d04f57d2086020c12e7eddb7","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/db9d8e3b670f841755bc2018f178472dc6064d27","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-74586","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}