Kernel: SCTP ASCONF Transport Dereference Vulnerability
CVE-2026-64564 Published on August 4, 2026
sctp: don't free the ASCONF's own transport in DEL-IP processing
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.
Products Associated with CVE-2026-64564
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Affected Versions
Linux:- Version 42e30bf3463cd37d73839376662cb79b4d5c416c and below fedeb4468987bcaff85fe3061de5ae052d414740 is affected.
- Version 42e30bf3463cd37d73839376662cb79b4d5c416c and below 74e8f3e7114f0e26d1b2c4c048044db9fcc27603 is affected.
- Version 42e30bf3463cd37d73839376662cb79b4d5c416c and below 85aca407c560aba81b5ce9d3d6cf94c74077d19b is affected.
- Version 42e30bf3463cd37d73839376662cb79b4d5c416c and below d136b29bf91dd8e3161281b87de597b7311d9462 is affected.
- Version 42e30bf3463cd37d73839376662cb79b4d5c416c and below 9b2854f86f0b56e9027d68e7a3fc909d1a9b566f is affected.
- Version 2.6.25 is affected.
- Before 2.6.25 is unaffected.
- Version 6.6.148, <= 6.6.* is unaffected.
- Version 6.12.101, <= 6.12.* is unaffected.
- Version 6.18.42, <= 6.18.* is unaffected.
- Version 7.1.6, <= 7.1.* is unaffected.
- Version 7.2-rc5, <= * is unaffected.