{"id":"CVE-2026-89477","title":"sctp: fix NULL deref on untransmitted RECONF completion","summary":"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…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","cwe":["CWE-476"],"vendor":"Linux","product":"Linux","affected":["Linux >= 81054476453640159149cb6704e834893e16736b < 79ff751311e80fa0370007e46a79a6d601685e75","Linux >= 81054476453640159149cb6704e834893e16736b < 53141db979687eae7dc6d29414cefc77034f967e","Linux >= 81054476453640159149cb6704e834893e16736b < 68891125af5a5dfbca728809a16637a869bbe0df","Linux >= 81054476453640159149cb6704e834893e16736b < b2d6d873b4dfb5b84194061c4b40a1cd85b92ca4","Linux >= 81054476453640159149cb6704e834893e16736b < 77ea60f2d24002c308f224db44a4542c466489af","Linux >= 81054476453640159149cb6704e834893e16736b < 25419f516ea84b1e7d3d55aae5215ac86ece0c66","Linux >= 81054476453640159149cb6704e834893e16736b < 0ee697defc0594f1da810ed75d9d643fb46f5318","Linux >= 81054476453640159149cb6704e834893e16736b < 2db9bfa3e27bdea15e05ea70b56bad3d21e570ec","Linux 4.11"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-16T19:22:22.091820Z"},"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:47:26.175Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89477","references":[{"url":"https://git.kernel.org/stable/c/79ff751311e80fa0370007e46a79a6d601685e75"},{"url":"https://git.kernel.org/stable/c/53141db979687eae7dc6d29414cefc77034f967e"},{"url":"https://git.kernel.org/stable/c/68891125af5a5dfbca728809a16637a869bbe0df"},{"url":"https://git.kernel.org/stable/c/b2d6d873b4dfb5b84194061c4b40a1cd85b92ca4"},{"url":"https://git.kernel.org/stable/c/77ea60f2d24002c308f224db44a4542c466489af"},{"url":"https://git.kernel.org/stable/c/25419f516ea84b1e7d3d55aae5215ac86ece0c66"},{"url":"https://git.kernel.org/stable/c/0ee697defc0594f1da810ed75d9d643fb46f5318"},{"url":"https://git.kernel.org/stable/c/2db9bfa3e27bdea15e05ea70b56bad3d21e570ec"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89477.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89477"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532238"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89477"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89477"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89477.mbox"}],"tags":["cve.org","csaf","vex","red-hat"],"epss":0.00501,"epssPercentile":0.42711,"scores":{"cna":7.5,"vendor":7},"ingestedAt":"2026-09-14T15:23:07.453Z","slug":"CVE-2026-89477","body":"## Overview\n\nIn 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->strreset_chunk->transport;\n\tif (timer_delete(&t->reconf_timer))\n\t\tsctp_transport_put(t);\n\nchunk->transport 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->strreset_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->src_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   <IRQ>\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   </IRQ>\n\nA response can only acknowledge a request that was actually sent, so do\nnot match asoc->strreset_chunk while chunk->transport is NULL. Guarding\nthe lookup covers all three completion sites.\n\n## Affected\n\n- `Linux >= 81054476453640159149cb6704e834893e16736b < 79ff751311e80fa0370007e46a79a6d601685e75`\n- `Linux >= 81054476453640159149cb6704e834893e16736b < 53141db979687eae7dc6d29414cefc77034f967e`\n- `Linux >= 81054476453640159149cb6704e834893e16736b < 68891125af5a5dfbca728809a16637a869bbe0df`\n- `Linux >= 81054476453640159149cb6704e834893e16736b < b2d6d873b4dfb5b84194061c4b40a1cd85b92ca4`\n- `Linux >= 81054476453640159149cb6704e834893e16736b < 77ea60f2d24002c308f224db44a4542c466489af`\n- `Linux >= 81054476453640159149cb6704e834893e16736b < 25419f516ea84b1e7d3d55aae5215ac86ece0c66`\n- `Linux >= 81054476453640159149cb6704e834893e16736b < 0ee697defc0594f1da810ed75d9d643fb46f5318`\n- `Linux >= 81054476453640159149cb6704e834893e16736b < 2db9bfa3e27bdea15e05ea70b56bad3d21e570ec`\n- `Linux 4.11`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89477.json)","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":223321,"id":"CVE-2026-89477","ts":1792180056393,"field":"cvss","old":"7","new":"7.5"},{"seq":206967,"id":"CVE-2026-89477","ts":1789749722886,"field":"cvss","old":"7.5","new":"7"},{"seq":198028,"id":"CVE-2026-89477","ts":1789384321456,"field":"cvss","old":"5.9","new":"7.5"},{"seq":198027,"id":"CVE-2026-89477","ts":1789384321456,"field":"severity","old":"medium","new":"high"},{"seq":183799,"id":"CVE-2026-89477","ts":1789356677442,"field":"cvss","old":"7.5","new":"5.9"},{"seq":183798,"id":"CVE-2026-89477","ts":1789356677442,"field":"severity","old":"high","new":"medium"},{"seq":153254,"id":"CVE-2026-89477","ts":1789285349755,"field":"cvss","old":null,"new":"7.5"},{"seq":153253,"id":"CVE-2026-89477","ts":1789285349755,"field":"severity","old":"none","new":"high"},{"seq":147580,"id":"CVE-2026-89477","ts":1789270211467,"field":"cvss","old":null,"new":"5.9"},{"seq":147579,"id":"CVE-2026-89477","ts":1789270211467,"field":"severity","old":"none","new":"medium"},{"seq":109330,"id":"CVE-2026-89477","ts":1789183731451,"field":"cvss","old":null,"new":"5.9"},{"seq":109329,"id":"CVE-2026-89477","ts":1789183731451,"field":"severity","old":"none","new":"medium"}]}