GHSA-H62F-42CP-XR87
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32In the Linux kernel, the following vulnerability has been resolved:
sctp: fix NULL deref on untransmitted RECONF completion
sctp_process_strreset_outreq(), sctp_process_strreset_addstrm_out() and sctp_process_strreset_resp() complete a pending stream reconfiguration request by stopping the reconf timer on the transport it was sent on:
t = asoc->strreset_chunk->transport;
if (timer_delete(&t->reconf_timer))
sctp_transport_put(t);
chunk->transport is assigned by __sctp_packet_append_chunk() when the chunk is appended to an outbound packet, and sctp_outq_flush_ctrl() arms the reconf timer at that same point. A request already published in asoc->strreset_chunk but not yet transmitted has neither, so completing it dereferences NULL.
Two ways to get there. sctp_send_asconf_del_ip() sets asoc->src_out_of_asoc_ok without sending anything when the address being removed is the association's last one, and sctp_outq_flush_ctrl() then leaves every non-ASCONF control chunk queued; as only sctp_process_asconf_ack() clears that flag, it persists. An unprivileged process that removes such an address and then asks for a stream reset panics the kernel from softirq. A peer needs neither ASCONF nor local help: sctp_cmd_interpreter() uncorks the outqueue only once the whole packet has been processed, so a reply built while walking a RECONF chunk stays untransmitted for the rest of that walk, and one RECONF chunk carrying [Incoming SSN Reset Request, Outgoing SSN Reset Request, Response] -- or two RECONF chunks in one packet -- reaches the same dereference.
KASAN: null-ptr-deref in range [0x00000000000001e8-0x00000000000001ef] RIP: 0010:timer_delete+0x67/0x110 Call Trace: sctp_process_strreset_addstrm_out (net/sctp/stream.c:832) sctp_sf_do_reconf (net/sctp/sm_statefuns.c:4212) sctp_do_sm (net/sctp/sm_sideeffect.c:1172) sctp_assoc_bh_rcv (net/sctp/associola.c:1044) sctp_rcv (net/sctp/input.c:243) ip_local_deliver (net/ipv4/ip_input.c:262) process_backlog (net/core/dev.c:6680)
A response can only acknowledge a request that was actually sent, so do not match asoc->strreset_chunk while chunk->transport is NULL. Guarding the lookup covers all three completion sites.
{
"affected": [],
"aliases": [
"CVE-2026-89477"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:29Z",
"severity": "HIGH"
},
"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(\u0026t-\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\u0027s 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.",
"id": "GHSA-h62f-42cp-xr87",
"modified": "2026-09-14T15:32:25Z",
"published": "2026-09-11T21:31:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89477"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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