A Linux kernel flaw nearly two decades old has yielded host root and a container escape in Tencent’s testing, and the researchers credit an AI pipeline for finding it. Dubbed SCTPhantom and tracked as CVE-2026-64564, the flaw dates to 2008 and has shipped in every kernel since.
The vulnerability sits in SCTP’s dynamic address reconfiguration. The kernel validates a delete request against the packet’s source address, then acts on a path selected using a different address inside the message. A message that carries an address, a delete for that address, and a wildcard delete frees the path and reuses the dead pointer, leaving the connection pointing at released memory.
Kernel maintainers shipped the fix August 3 in stable releases 7.1.6, 6.18.42, 6.12.101, and 6.6.148. Tencent rates the vulnerability 8.5 under CVSS v4.0; NVD had not published a severity rating as of August 7.
The bug is only exploitable locally and requires SCTP to be reachable on the victim, narrowing the attack surface. When those conditions line up, Tencent Zhuque Lab says it achieved root on its Debian 13, Ubuntu 24.04, Rocky Linux 9, RHEL 9, and OpenCloudOS test builds. The container escape ran with the default seccomp profile and without CAP_NET_ADMIN or CAP_SYS_ADMIN, reaching host root in six of eight attempts. The finding has not been independently reproduced, and the write-up omits the container runtime used in testing.
For defenders, the practical step is simple: if SCTP is not in use, disable the module and the exposure disappears. Teams that must run it should verify their kernel builds carry the August 3 fix, keeping in mind that the same stable releases also address Zapscape, an unrelated KVM escape disclosed the same day. Tencent says an automated research pipeline called Corvus AI surfaced the bug, the latest in a string of aged kernel flaws that machine-assisted analysis has revived this year.
