{"id":"CVE-2026-89477","summary":"sctp: fix NULL deref on untransmitted RECONF completion","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: fix NULL deref on untransmitted RECONF completion\n\nsctp_process_strreset_outreq(), sctp_process_strreset_addstrm_out() and\nsctp_process_strreset_resp() complete a pending stream reconfiguration\nrequest by stopping the reconf timer on the transport it was sent on:\n\n\tt = asoc-\u003estrreset_chunk-\u003etransport;\n\tif (timer_delete(&t-\u003ereconf_timer))\n\t\tsctp_transport_put(t);\n\nchunk-\u003etransport is assigned by __sctp_packet_append_chunk() when the\nchunk is appended to an outbound packet, and sctp_outq_flush_ctrl() arms\nthe reconf timer at that same point. A request already published in\nasoc-\u003estrreset_chunk but not yet transmitted has neither, so completing\nit dereferences NULL.\n\nTwo ways to get there. sctp_send_asconf_del_ip() sets\nasoc-\u003esrc_out_of_asoc_ok without sending anything when the address being\nremoved is the association's last one, and sctp_outq_flush_ctrl() then\nleaves every non-ASCONF control chunk queued; as only\nsctp_process_asconf_ack() clears that flag, it persists. An unprivileged\nprocess that removes such an address and then asks for a stream reset\npanics the kernel from softirq. A peer needs neither ASCONF nor local\nhelp: sctp_cmd_interpreter() uncorks the outqueue only once the whole\npacket has been processed, so a reply built while walking a RECONF chunk\nstays untransmitted for the rest of that walk, and one RECONF chunk\ncarrying [Incoming SSN Reset Request, Outgoing SSN Reset Request,\nResponse] -- or two RECONF chunks in one packet -- reaches the same\ndereference.\n\n  KASAN: null-ptr-deref in range [0x00000000000001e8-0x00000000000001ef]\n  RIP: 0010:timer_delete+0x67/0x110\n  Call Trace:\n   \u003cIRQ\u003e\n   sctp_process_strreset_addstrm_out (net/sctp/stream.c:832)\n   sctp_sf_do_reconf (net/sctp/sm_statefuns.c:4212)\n   sctp_do_sm (net/sctp/sm_sideeffect.c:1172)\n   sctp_assoc_bh_rcv (net/sctp/associola.c:1044)\n   sctp_rcv (net/sctp/input.c:243)\n   ip_local_deliver (net/ipv4/ip_input.c:262)\n   process_backlog (net/core/dev.c:6680)\n   \u003c/IRQ\u003e\n\nA response can only acknowledge a request that was actually sent, so do\nnot match asoc-\u003estrreset_chunk while chunk-\u003etransport is NULL. Guarding\nthe lookup covers all three completion sites.","modified":"2026-09-18T18:26:39.847757910Z","published":"2026-09-11T19:43:33.851Z","related":["openSUSE-SU-2026:11805-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89477.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0ee697defc0594f1da810ed75d9d643fb46f5318"},{"type":"WEB","url":"https://git.kernel.org/stable/c/25419f516ea84b1e7d3d55aae5215ac86ece0c66"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2db9bfa3e27bdea15e05ea70b56bad3d21e570ec"},{"type":"WEB","url":"https://git.kernel.org/stable/c/53141db979687eae7dc6d29414cefc77034f967e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/68891125af5a5dfbca728809a16637a869bbe0df"},{"type":"WEB","url":"https://git.kernel.org/stable/c/77ea60f2d24002c308f224db44a4542c466489af"},{"type":"WEB","url":"https://git.kernel.org/stable/c/79ff751311e80fa0370007e46a79a6d601685e75"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b2d6d873b4dfb5b84194061c4b40a1cd85b92ca4"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89477.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89477"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"81054476453640159149cb6704e834893e16736b"},{"fixed":"79ff751311e80fa0370007e46a79a6d601685e75"},{"fixed":"53141db979687eae7dc6d29414cefc77034f967e"},{"fixed":"68891125af5a5dfbca728809a16637a869bbe0df"},{"fixed":"b2d6d873b4dfb5b84194061c4b40a1cd85b92ca4"},{"fixed":"77ea60f2d24002c308f224db44a4542c466489af"},{"fixed":"25419f516ea84b1e7d3d55aae5215ac86ece0c66"},{"fixed":"0ee697defc0594f1da810ed75d9d643fb46f5318"},{"fixed":"2db9bfa3e27bdea15e05ea70b56bad3d21e570ec"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-89477.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.11.0"},{"fixed":"5.10.270"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.221"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.188"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.157"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.109"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.50"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-89477.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}