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

1. In CISA KEV: not seen
2. Exploited (reported): not seen
3. Scanning observed: not seen
4. Proof of concept public5 public GitHub repositories (unverified), listed by PoC-in-GitHub7 Aug
5. Not established: not seen

DescriptionNVD

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.

Exploitation

Possible (1 to 10%). EPSS between 1% and 10%.

CISA KEV

Not listed

Public check

No public nuclei template

Weakness

Use After Free · Memory Corruption

Vendor

Linux

Published

August 2026

Band

Possible (1 to 10%), August 2026

1. 7 Aug
   PoC-in-GitHub lists 5 public GitHub repositories (unverified) PoC-in-GitHub

• NVD entrynvd.nist.gov
• Vendor advisoryopenwall.com
• CVE recordcve.org