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Public proof of conceptFix available

CVE-2026-64564

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

A public proof of concept exists; no exploitation attested.

  • Published2026-08-04
  • WeaknessCWE-416

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2026-08-0407:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-64564?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-64564?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • kernelAlmaLinux:9all versions · fixed in 5.14.0-687.51.1.el9_8and 16 other packages
  • kernelAlmaLinux:8all versions · fixed in 4.18.0-553.167.1.el8_10and 24 other packages
  • kernel-develAlmaLinux:10all versions · fixed in 6.12.0-211.59.1.el10_2and 13 other packages
  • kernel-rtAlmaLinux:8all versions · fixed in 4.18.0-553.167.1.rt7.508.el8_10and 9 other packages

Vendor advisories

  • CVE-2026-64564 Red Hat Product Security2,227 products fixed · 24 known affected

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

    kernel-rt as a component of Red Hat Enterprise Linux 9 · kernel-rt-core as a component of Red Hat Enterprise Linux 9 · kernel-rt-debug as a component of Red Hat Enterprise Linux 9 · +21 more

  • RHSA-2026:71232 Red Hat Product Security303 products fixed

    Red Hat Security Advisory: kernel security, bug fix, and enhancement update

  • RHSA-2026:71233 Red Hat Product Security309 products fixed

    Red Hat Security Advisory: kernel security, bug fix, and enhancement update

  • RHSA-2026:71213 Red Hat Product Security120 products fixed

    Red Hat Security Advisory: kernel security, bug fix, and enhancement update

  • RHSA-2026:71016 Red Hat Product Security30 products fixed

    Red Hat Security Advisory: kernel-rt security, bug fix, and enhancement update

  • RHSA-2026:70484 Red Hat Product Security305 products fixed

    Red Hat Security Advisory: kernel security, bug fix, and enhancement update

9 more advisories

Full record on NVD

Fix

  1. Vendor fix Red Hat Product Security RHSA-2026:71232 · 303 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 The system must be rebooted for this update to take effect. Red Hat recommends treating all kernel errata as security-relevant. Given the kernel's fu…
  2. Workaround from the vendor Red Hat Product Security RHSA-2026:71232 · 303 productsTo mitigate this issue, prevent the `sctp` kernel module from loading. Create a file named `/etc/modprobe.d/disable-sctp.conf` with the following content: ``` install sctp /bin/true blacklist sctp ``` After creating the file, regenerate the initramfs and reboot the system for the changes to take …

Detection

read 2026-10-23 19:25 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
5 repositories, unverifiedethanolgolf/CVE-2026-64564HackSpeak/CVE-2026-64564suominen/sctphantomyandex-cloud-examples/yc-mk8s-sctphantom-mitigation0xdeadroot/SCTPhantom-CVE-2026-64564
PoC-in-GitHub

Sources

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2026-08-04
Last Modified
2026-10-19
NVD status
Received

Frequently asked questions

What is CVE-2026-64564?

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.

Is CVE-2026-64564 actively exploited?

Active exploitation of CVE-2026-64564 has not been confirmed. Its EPSS score was 1.4% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-64564?

CVE-2026-64564 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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