Critical 9.8Published Aug 4, 2026

CVE-2026-64564sctp: don't free the ASCONF's own transport in DEL-IP processing

Updated under an hour ago (Oct 26, 2026, 6:20 PM ET)

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: sctp: don't free the ASCONF's own transport in DEL-IP processing sctp_process_asconf() caches the transport the ASCONF chunk is processed against in asconf->transport (== chunk->transport, set once in sctp_rcv()). For an ASCONF located through its Address Parameter by __sctp_rcv_asconf_lookup(), that cached transport corresponds to the Address Parameter, which need not be the packet's source address. sctp_process_asconf_param() rejects a DEL-IP for the packet source address (ADDIP D8, SCTP_ERROR_DEL_SRC_IP), but nothing protects asconf->transport. A single ASCONF can therefore carry, in order: [Address Parameter L] [DEL-IP L] [DEL-IP 0.0.0.0] where L differs from the source. The DEL-IP for L passes the D8 check and calls sctp_assoc_rm_peer() on the transport that asconf->transport still points at, freeing it (RCU-deferred). The following wildcard DEL-IP then reuses the now-dangling asconf->transport in sctp_assoc_set_primary() and sctp_assoc_del_nonprimary_peers(): set_primary() dereferences the freed transport (->ipaddr, ->state) and plants the dangling pointer into asoc->peer.primary_path / active_path, and del_nonprimary_peers(), keeping only the pointer that is no longer on the list, removes every real transport, leaving the association with a transport_count of 0 and primary_path/active_path pointing at freed memory. Reject a DEL-IP that targets the transport the ASCONF is being processed against, mirroring the existing source-address guard, so the wildcard branch can never reuse a freed transport.

CVSS: 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-416
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Received
Record last updated: Oct 19, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 42e30bf3463cd37d73839376662cb79b4d5c416c before a9ce31be4cb1a5dd82b3e0a1d0c3e7cbdcd31293; from 42e30bf3463cd37d73839376662cb79b4d5c416c before a63afa1f9b12d5293cbe0b77fd45dc0632533a13; 42e30bf3463cd37d73839376662cb79b4d5c416c builds before 2b324ba3494ae958cba16a453e3e71489b4de7fc; from 42e30bf3463cd37d73839376662cb79b4d5c416c before fedeb4468987bcaff85fe3061de5ae052d414740; from 42e30bf3463cd37d73839376662cb79b4d5c416c before 74e8f3e7114f0e26d1b2c4c048044db9fcc27603; from 42e30bf3463cd37d73839376662cb79b4d5c416c before 85aca407c560aba81b5ce9d3d6cf94c74077d19b; from 42e30bf3463cd37d73839376662cb79b4d5c416c before d136b29bf91dd8e3161281b87de597b7311d9462; 42e30bf3463cd37d73839376662cb79b4d5c416c builds before 9b2854f86f0b56e9027d68e7a3fc909d1a9b566f	CNA record

References

References

https://git.kernel.org/stable/c/a9ce31be4cb1a5dd82b3e0a1d0c3e7cbdcd31293
https://git.kernel.org/stable/c/a63afa1f9b12d5293cbe0b77fd45dc0632533a13
https://git.kernel.org/stable/c/2b324ba3494ae958cba16a453e3e71489b4de7fc
https://git.kernel.org/stable/c/fedeb4468987bcaff85fe3061de5ae052d414740
https://git.kernel.org/stable/c/74e8f3e7114f0e26d1b2c4c048044db9fcc27603
https://git.kernel.org/stable/c/85aca407c560aba81b5ce9d3d6cf94c74077d19b
https://git.kernel.org/stable/c/d136b29bf91dd8e3161281b87de597b7311d9462
https://git.kernel.org/stable/c/9b2854f86f0b56e9027d68e7a3fc909d1a9b566f
https://matrix.tencent.com/en/2026/08/06/sctphantom-CVE-2026-64564
http://www.openwall.com/lists/oss-security/2026/08/06/13
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The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.