GHSA-P4VF-G6H3-F897
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: clear new_transport when removing a peer
sctp_process_asconf_param() stores a newly added peer transport in asoc->new_transport. After all parameters in the ASCONF chunk have been processed, sctp_sf_do_asconf() uses this pointer to send a HEARTBEAT to the new transport.
An authenticated ASCONF from a remote SCTP peer can add a transport and remove it again with a wildcard DEL-IP parameter in the same chunk. The wildcard deletion preserves the transport on which the ASCONF arrived, but removes the newly added transport through sctp_assoc_del_nonprimary_peers(). The removal does not clear asoc->new_transport, leaving it pointing to the removed transport.
sctp_sf_do_asconf() then creates a HEARTBEAT whose chunk->transport points to the removed transport without holding a transport reference. During local address replacement, src_out_of_asoc_ok keeps this HEARTBEAT on control_chunk_list. After the transport is freed by RCU, a successful ASCONF_ACK for the replacement address releases the queued HEARTBEAT and sctp_outq_select_transport() reads the freed transport's state.
The issue was found during a static audit of SCTP objects. With an authenticated peer, the reproducer triggered the same KASAN report in 2 of 2 unpatched runs on a KASAN-enabled netdev/main kernel:
BUG: KASAN: slab-use-after-free in sctp_outq_select_transport Read of size 4 at addr ffff88800b9bd95c by task python3/197
Call Trace: sctp_outq_select_transport+0x549/0x8b0 [sctp] sctp_outq_flush+0x306/0x2c60 [sctp] sctp_transport_immediate_rtx+0xaf/0x260 [sctp] sctp_process_asconf_ack+0xa48/0xf70 [sctp]
Allocated by task 197: sctp_transport_new+0x68/0x650 [sctp] sctp_assoc_add_peer+0x258/0x12a0 [sctp] sctp_process_asconf+0x5e9/0x1090 [sctp]
Last potentially related work creation: __call_rcu_common.constprop.0+0x77/0xb70 sctp_assoc_del_nonprimary_peers+0x7c/0xd0 [sctp] sctp_process_asconf+0xd9c/0x1090 [sctp]
The first invalid access was a four-byte read of transport->state at net/sctp/outqueue.c:833. The same reproducer completed the full authenticated ASCONF and local-address replacement sequence with this change without a KASAN report or oops.
Clear new_transport when its peer is removed, before it can be used to create the HEARTBEAT.
{
"affected": [],
"aliases": [
"CVE-2026-74586"
],
"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: clear new_transport when removing a peer\n\nsctp_process_asconf_param() stores a newly added peer transport in\nasoc-\u003enew_transport. After all parameters in the ASCONF chunk have been\nprocessed, sctp_sf_do_asconf() uses this pointer to send a HEARTBEAT to the\nnew transport.\n\nAn authenticated ASCONF from a remote SCTP peer can add a transport and\nremove it again with a wildcard DEL-IP parameter in the same chunk. The\nwildcard deletion preserves the transport on which the ASCONF arrived, but\nremoves the newly added transport through\nsctp_assoc_del_nonprimary_peers(). The removal does not clear\nasoc-\u003enew_transport, leaving it pointing to the removed transport.\n\nsctp_sf_do_asconf() then creates a HEARTBEAT whose chunk-\u003etransport points\nto the removed transport without holding a transport reference. During\nlocal address replacement, src_out_of_asoc_ok keeps this HEARTBEAT on\ncontrol_chunk_list. After the transport is freed by RCU, a successful\nASCONF_ACK for the replacement address releases the queued HEARTBEAT and\nsctp_outq_select_transport() reads the freed transport\u0027s state.\n\nThe issue was found during a static audit of SCTP objects. With an\nauthenticated peer, the reproducer triggered the same KASAN report in 2\nof 2 unpatched runs on a KASAN-enabled netdev/main kernel:\n\n BUG: KASAN: slab-use-after-free in sctp_outq_select_transport\n Read of size 4 at addr ffff88800b9bd95c by task python3/197\n\n Call Trace:\n sctp_outq_select_transport+0x549/0x8b0 [sctp]\n sctp_outq_flush+0x306/0x2c60 [sctp]\n sctp_transport_immediate_rtx+0xaf/0x260 [sctp]\n sctp_process_asconf_ack+0xa48/0xf70 [sctp]\n\n Allocated by task 197:\n sctp_transport_new+0x68/0x650 [sctp]\n sctp_assoc_add_peer+0x258/0x12a0 [sctp]\n sctp_process_asconf+0x5e9/0x1090 [sctp]\n\n Last potentially related work creation:\n __call_rcu_common.constprop.0+0x77/0xb70\n sctp_assoc_del_nonprimary_peers+0x7c/0xd0 [sctp]\n sctp_process_asconf+0xd9c/0x1090 [sctp]\n\nThe first invalid access was a four-byte read of transport-\u003estate at\nnet/sctp/outqueue.c:833. The same reproducer completed the full\nauthenticated ASCONF and local-address replacement sequence with this\nchange without a KASAN report or oops.\n\nClear new_transport when its peer is removed, before it can be used to\ncreate the HEARTBEAT.",
"id": "GHSA-p4vf-g6h3-f897",
"modified": "2026-08-25T06:31:21Z",
"published": "2026-08-22T18:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74586"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/163847552a571bd55094291f4ffcdc1de0f14a7b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/291accf36febce751021888de5f15090f4875b56"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/31efa656cf6aface26e88f038c14f22ee6ca1500"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3b539b317cd052236fed0350364ff1268996ba46"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/beb33f8ee1ca83acddb2a5ae80f3d22ec550b4c3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c0f973bb5118dd1b146cda3fcc8af6f6057befec"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ca33df36aa0143a1d04f57d2086020c12e7eddb7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/db9d8e3b670f841755bc2018f178472dc6064d27"
}
],
"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"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.