GHSA-5VMC-FX99-R54R
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: fix use-after-free of cached ASCONF chunk
addip_last_asconf caches the outstanding outbound ASCONF chunk. The normal ASCONF-ACK completion path releases the chunk and clears the pointer.
However, sctp_asconf_queue_teardown() releases the cached chunk without clearing addip_last_asconf. During peer restart handling, sctp_sf_do_dupcook_a() queues SCTP_CMD_PURGE_ASCONF_QUEUE, which invokes sctp_asconf_queue_teardown() while the association remains alive and leaves the pointer dangling.
A delayed authenticated ASCONF-ACK can then reach sctp_sf_do_asconf_ack(), which accesses the stale chunk and passes it to sctp_process_asconf_ack(), causing a use-after-free and a second release.
Clearing the pointer exposes a race with T4 expiry. Peer restart handling queues the timer stop before the purge, but SCTP_CMD_TIMER_STOP uses timer_delete(), which does not wait for a callback already running on another CPU. Such a callback can reach sctp_sf_t4_timer_expire() after the purge and dereference NULL.
Clear addip_last_asconf after releasing the cached chunk, and make sctp_sf_t4_timer_expire() consume a stale T4 expiry if no outstanding ASCONF remains.
{
"affected": [],
"aliases": [
"CVE-2026-74587"
],
"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: fix use-after-free of cached ASCONF chunk\n\naddip_last_asconf caches the outstanding outbound ASCONF chunk. The normal\nASCONF-ACK completion path releases the chunk and clears the pointer.\n\nHowever, sctp_asconf_queue_teardown() releases the cached chunk without\nclearing addip_last_asconf. During peer restart handling,\nsctp_sf_do_dupcook_a() queues SCTP_CMD_PURGE_ASCONF_QUEUE, which invokes\nsctp_asconf_queue_teardown() while the association remains alive and leaves\nthe pointer dangling.\n\nA delayed authenticated ASCONF-ACK can then reach sctp_sf_do_asconf_ack(),\nwhich accesses the stale chunk and passes it to sctp_process_asconf_ack(),\ncausing a use-after-free and a second release.\n\nClearing the pointer exposes a race with T4 expiry. Peer restart handling\nqueues the timer stop before the purge, but SCTP_CMD_TIMER_STOP uses\ntimer_delete(), which does not wait for a callback already running on\nanother CPU. Such a callback can reach sctp_sf_t4_timer_expire() after\nthe purge and dereference NULL.\n\nClear addip_last_asconf after releasing the cached chunk, and make\nsctp_sf_t4_timer_expire() consume a stale T4 expiry if no outstanding\nASCONF remains.",
"id": "GHSA-5vmc-fx99-r54r",
"modified": "2026-08-25T06:31:21Z",
"published": "2026-08-22T18:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74587"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/07daf4f9750104960a1d60831b2353c0d41f35fb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/10459b03e2d9ee12435e96f587de4d4cacdbf435"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/179676f0166230c80053a392303485b37c93dd33"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/618b5c6d049896fcfabb91afc072954c92cb2693"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8c283e7b56adce00193837f3311b06662466fb21"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d949992bc3f00027a2c755e860a11950c75f6073"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dc67d528c2fa939cec7fe3bf7f3089c8d281ca3d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e1bb114e09372fd6e03387ced9ef566da336ed6c"
}
],
"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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