CVE-2026-74587 (GCVE-0-2026-74587)
Vulnerability from cvelistv5
Published
2026-08-22 15:31
Modified
2026-08-25 05:40
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In 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.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: a000c01e60e40e15304ffe48fff051d17a7bea91 Version: a000c01e60e40e15304ffe48fff051d17a7bea91 Version: a000c01e60e40e15304ffe48fff051d17a7bea91 Version: a000c01e60e40e15304ffe48fff051d17a7bea91 Version: a000c01e60e40e15304ffe48fff051d17a7bea91 Version: a000c01e60e40e15304ffe48fff051d17a7bea91 Version: a000c01e60e40e15304ffe48fff051d17a7bea91 Version: a000c01e60e40e15304ffe48fff051d17a7bea91 |
||
{
"containers": {
"cna": {
"affected": [
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"product": "Linux",
"programFiles": [
"net/sctp/associola.c",
"net/sctp/sm_statefuns.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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],
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"vendor": "Linux",
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"status": "unaffected",
"version": "0",
"versionType": "semver"
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{
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"status": "unaffected",
"version": "5.15.216",
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{
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"version": "6.1.183",
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{
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"version": "6.6.152",
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{
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{
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"version": "7.1.9",
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},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
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],
"negate": false,
"operator": "OR"
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],
"descriptions": [
{
"lang": "en",
"value": "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."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - The UAF is triggered when the kernel processes inbound SCTP COOKIE-ECHO (peer restart) and ASCONF-ACK chunks from a remote association peer via sctp_rcv()/sctp_inq_push()/sctp_do_sm(), with no local syscall required on the victim.\nAC:L - The remote SCTP peer controls the full protocol sequence\u2014establishing an ADDIP-capable association, waiting for the victim\u0027s outstanding ASCONF, sending COOKIE-ECHO restart to purge queues, then delivering a delayed authenticated ASCONF-ACK\u2014without attacker-uncontrollable races or memory layout.\nPR:N - Exploitation requires only network access as an established SCTP association peer sending authenticated protocol traffic; no local Linux account, capability, or namespace privilege is needed on the victim host.\nUI:N - No victim user action is required beyond normal automated SCTP server/client operation; the attacker drives the entire trigger sequence with crafted COOKIE-ECHO and ASCONF-ACK packets on the existing association.\nS:U - Impact is confined to kernel memory corruption and potential privilege escalation within the host kernel; it does not cross a VM, container, or IOMMU security boundary.\nC:H - sctp_sf_do_asconf_ack() and sctp_process_asconf_ack() dereference the stale addip_last_asconf pointer to read freed sctp_chunk and skb metadata; UAF on slab-allocated chunk objects enables heap grooming for arbitrary kernel memory disclosure.\nI:H - The stale pointer causes sctp_process_asconf_ack() to perform a second sctp_chunk_free() on an already-freed chunk, yielding a kmem_cache double-free that can be leveraged for arbitrary kernel write or control-flow hijack.\nA:H - Dereferencing the freed cached ASCONF chunk during ASCONF-ACK processing can cause kernel oops/panic and repeatable remote denial of service against any SCTP endpoint handling the malicious peer traffic."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:40:13.798Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/10459b03e2d9ee12435e96f587de4d4cacdbf435"
},
{
"url": "https://git.kernel.org/stable/c/e1bb114e09372fd6e03387ced9ef566da336ed6c"
},
{
"url": "https://git.kernel.org/stable/c/179676f0166230c80053a392303485b37c93dd33"
},
{
"url": "https://git.kernel.org/stable/c/dc67d528c2fa939cec7fe3bf7f3089c8d281ca3d"
},
{
"url": "https://git.kernel.org/stable/c/618b5c6d049896fcfabb91afc072954c92cb2693"
},
{
"url": "https://git.kernel.org/stable/c/07daf4f9750104960a1d60831b2353c0d41f35fb"
},
{
"url": "https://git.kernel.org/stable/c/d949992bc3f00027a2c755e860a11950c75f6073"
},
{
"url": "https://git.kernel.org/stable/c/8c283e7b56adce00193837f3311b06662466fb21"
}
],
"title": "sctp: fix use-after-free of cached ASCONF chunk",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74587",
"datePublished": "2026-08-22T15:31:39.810Z",
"dateReserved": "2026-08-15T05:44:03.918Z",
"dateUpdated": "2026-08-25T05:40:13.798Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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