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CVE-2026-72243 is an improper access-control issue in the Linux kernel SELinux networking hooks. Before the fix, the SELinux socket_sendmsg() hook did not invoke selinux_socket_connect() for sendmsg() operations issued with the MSG_FASTOPEN flag. Consequently, TCP Fast Open connection attempts did not receive the normal SELinux connect-related permission checks. The fix calls selinux_socket_connect() when MSG_FASTOPEN is supplied, restoring enforcement of SELinux policy for these operations.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
The repository contains a README and one standalone Go proof of concept, test.go. It is not part of an exploit framework. The code defines a custom net.Conn implementation (tfoConn) backed directly by Linux syscalls. On its first Write, tfoConn calls sendto with MSG_FASTOPEN and the target SockaddrInet4; later writes use write(2), while reads use read(2). Go's crypto/tls client writes its ClientHello through this custom connection, making the initial network operation sendto(MSG_FASTOPEN) instead of connect(2). After the TLS handshake, the PoC submits a manually constructed HTTP/1.1 GET request and reads the complete response. The supplied main routine targets a Kubernetes API server at 10.10.10.10:6443/api/v1/, reads the in-container service-account token, and sends it as a Bearer credential. This is an operational but minimally robust PoC: target values are hard-coded, it accepts only IPv4 literals, disables TLS certificate verification, does not implement deadlines, assumes the initial Sendto transfers the full buffer, and has no retry or fallback logic. Its intended purpose is post-compromise/container reconnaissance or access where syscall-focused monitoring or policy rules cover connect(2) but fail to cover TCP Fast Open initialization via sendto(2).
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6 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Linux kernel SELinux authorization flaw involving connect-related permission checks for TCP Fast Open.
A Linux kernel vulnerability addressed by an AlmaLinux 9 kernel update; no flaw-specific technical detail is supplied.
A vulnerability addressed by the Rocky Linux 9 kernel update; technical details are not provided.
A Linux kernel SELinux authorization flaw in which connect-related SELinux permissions were not checked for TCP Fast Open connections using MSG_FASTOPEN, potentially allowing policy checks applicable to connection establishment to be bypassed.
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Every observed campaign linking this CVE to a named adversary.
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Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.