GHSA-G275-M9XC-X5Q2
Vulnerability from github – Published: 2026-08-22 18:30 – Updated: 2026-08-25 06:31In the Linux kernel, the following vulnerability has been resolved:
sctp: keep chunk->transport in step with the list it is queued on
__sctp_outq_flush_rtx() moves a gap-acked chunk onto another transport's transmitted list without updating chunk->transport:
if (chunk->tsn_gap_acked) {
list_move_tail(&chunk->transmitted_list,
&transport->transmitted);
continue;
}
The chunk then sits on a live transport's list while chunk->transport still names a different one. If that transport is removed - sctp_assoc_rm_peer() from an ASCONF Delete-IP - sctp_transport_free() RCU-frees it and the chunk is left with a dangling pointer. sctp_assoc_rm_peer() scrubs peer->transmitted and asoc->outqueue.out_chunk_list, but the chunk is on neither.
The pointer is not followed while tsn_gap_acked is set. A SACK that reneges on the TSN clears the flag, and the next SACK reaches
tchunk->transport->flight_size -= sctp_data_size(tchunk);
inside the freed transport. KASAN reports a slab-use-after-free read in sctp_check_transmitted(), freed from sctp_assoc_rm_peer(). Both the removal and the SACKs come from the association peer.
Set chunk->transport at the move. The ordinary resend path needs nothing: it reaches its list_move_tail() only after sctp_packet_append_chunk() returned SCTP_XMIT_OK, and __sctp_packet_append_chunk() has rebound the chunk by then.
Discovered by XBOW, triaged by Baul Lee baul.lee@xbow.com
{
"affected": [],
"aliases": [
"CVE-2026-74588"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-22T16:16:30Z",
"severity": "CRITICAL"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: keep chunk-\u003etransport in step with the list it is queued on\n\n__sctp_outq_flush_rtx() moves a gap-acked chunk onto another transport\u0027s\ntransmitted list without updating chunk-\u003etransport:\n\n\tif (chunk-\u003etsn_gap_acked) {\n\t\tlist_move_tail(\u0026chunk-\u003etransmitted_list,\n\t\t\t \u0026transport-\u003etransmitted);\n\t\tcontinue;\n\t}\n\nThe chunk then sits on a live transport\u0027s list while chunk-\u003etransport still\nnames a different one. If that transport is removed - sctp_assoc_rm_peer()\nfrom an ASCONF Delete-IP - sctp_transport_free() RCU-frees it and the chunk\nis left with a dangling pointer. sctp_assoc_rm_peer() scrubs\npeer-\u003etransmitted and asoc-\u003eoutqueue.out_chunk_list, but the chunk is on\nneither.\n\nThe pointer is not followed while tsn_gap_acked is set. A SACK that\nreneges on the TSN clears the flag, and the next SACK reaches\n\n\ttchunk-\u003etransport-\u003eflight_size -= sctp_data_size(tchunk);\n\ninside the freed transport. KASAN reports a slab-use-after-free read in\nsctp_check_transmitted(), freed from sctp_assoc_rm_peer(). Both the\nremoval and the SACKs come from the association peer.\n\nSet chunk-\u003etransport at the move. The ordinary resend path needs nothing:\nit reaches its list_move_tail() only after sctp_packet_append_chunk()\nreturned SCTP_XMIT_OK, and __sctp_packet_append_chunk() has rebound the\nchunk by then.\n\nDiscovered by XBOW, triaged by Baul Lee \u003cbaul.lee@xbow.com\u003e",
"id": "GHSA-g275-m9xc-x5q2",
"modified": "2026-08-25T06:31:21Z",
"published": "2026-08-22T18:30:25Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74588"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1adf929121e13e0b19200bb9fef715b918d483fe"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2b3b5eec8b2c30ee237e3c31a6a38de9c39d804d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5ccf35ef0ed6059cdf8b1f4606a6584d5b67166b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6575fb17230814b48b471727c8410c0aadff9274"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6b9e2ea2057113f3393990ba646d2d97c719a80d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/874a7c2b5e184f06134fdfde27e9ce9271bafe58"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9f2cf069a9a72a2d6b97ca8b4c70e714aac99749"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e2e7c1de0e226ca1b7fea2de57a6c9bca408709b"
}
],
"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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