GHSA-2F22-4VGF-P33P

Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

sctp: stop processing a packet once its association is deleted

sctp_endpoint_bh_rcv() looks the association up only when chunk->asoc is NULL, and caches the result in chunk->asoc and chunk->transport without taking a reference.

A packet that matches no association is handed to the endpoint, so a peer can bundle COOKIE ECHO, SHUTDOWN and SHUTDOWN ACK in one packet. The COOKIE ECHO creates the association, the SHUTDOWN chunk caches it, and with the outqueue empty the SHUTDOWN ACK reaches sctp_sf_do_9_2_final(), so the association and its transports are freed.

The endpoint loop has no counterpart to the asoc->base.dead check in sctp_assoc_bh_rcv(). The next chunk writes to last_time_heard in the freed transport and is then passed to sctp_do_sm() with the freed association. The transport is freed through RCU, so this needs the packet to come off the socket backlog, where the loop runs in task context.

The endpoint loop cannot do the same check: it holds no reference on the association, so reading asoc->base.dead would itself be a use-after-free. Mark the packet for discard in the command interpreter, just before it deletes the association. That is also before sctp_inq_free() releases the chunk on the association receive path.

sctp_sf_do_5_2_4_dupcook() issues SCTP_CMD_DELETE_TCB for the temporary association, while the one the packet belongs to stays alive. A restarting peer can bundle DATA behind its COOKIE ECHO, so compare against chunk->asoc and leave that case alone.

Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-89479"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-11T20:19:29Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: stop processing a packet once its association is deleted\n\nsctp_endpoint_bh_rcv() looks the association up only when chunk-\u003easoc is\nNULL, and caches the result in chunk-\u003easoc and chunk-\u003etransport without\ntaking a reference.\n\nA packet that matches no association is handed to the endpoint, so a peer\ncan bundle COOKIE ECHO, SHUTDOWN and SHUTDOWN ACK in one packet. The\nCOOKIE ECHO creates the association, the SHUTDOWN chunk caches it, and\nwith the outqueue empty the SHUTDOWN ACK reaches sctp_sf_do_9_2_final(),\nso the association and its transports are freed.\n\nThe endpoint loop has no counterpart to the asoc-\u003ebase.dead check in\nsctp_assoc_bh_rcv(). The next chunk writes to last_time_heard in the freed\ntransport and is then passed to sctp_do_sm() with the freed association.\nThe transport is freed through RCU, so this needs the packet to come off\nthe socket backlog, where the loop runs in task context.\n\nThe endpoint loop cannot do the same check: it holds no reference on the\nassociation, so reading asoc-\u003ebase.dead would itself be a use-after-free.\nMark the packet for discard in the command interpreter, just before it\ndeletes the association. That is also before sctp_inq_free() releases the\nchunk on the association receive path.\n\nsctp_sf_do_5_2_4_dupcook() issues SCTP_CMD_DELETE_TCB for the temporary\nassociation, while the one the packet belongs to stays alive. A restarting\npeer can bundle DATA behind its COOKIE ECHO, so compare against\nchunk-\u003easoc and leave that case alone.",
  "id": "GHSA-2f22-4vgf-p33p",
  "modified": "2026-09-14T15:32:26Z",
  "published": "2026-09-11T21:31:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89479"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/09c3b193a3e8fe53e1f416e2f8e3283d2a785405"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/47e15a8d12e366d0d261bcbc394394f44418938d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5c0b2dbbdafc9eeeb11fffe1e46551fc3b55d8ee"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7d970353eeb98f46a3b9dc602850e4f6336a9889"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a713e1b3a265f180ad25a08e17be15d67a2f7149"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ed85fe91a61bc0e0da6b585c07102b20f4cc65a0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ee3f04cf566f6041aa9a0360494fd8db5ade383a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fa306a40e716c5abcd967475459ce1ebd56e5115"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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