Linux Kernel TCP Fast Open Flaw Can Leak Memory
Vulnerability Disclosure · 3 sources · Updated 2mo ago · First seen Aug 8, 2024
CVE-2021-47304 is a low-severity Linux kernel TCP flaw in tcp_init_transfer() that resets the icsk_ca_initialized state. A local low-privileged process can initiate a TCP Fast Open connection, change TCP congestion control while the socket remains in TCP_SYN_SENT, and cause congestion-control initialization to run twice without the required intervening release operation. Modules such as CDG that allocate memory during initialization can leak memory, creating an availability impact.
The flaw was introduced in Linux 5.10 and fixed upstream in kernel versions 5.10.53, 5.13.5, and 5.14. Red Hat assigned a CVSS v3.1 score of 5.5 and remediated affected RHEL 8 kernel and kernel-rt packages through RHSA-2024:5101 and RHSA-2024:5102; RHEL 9 is not affected, while RHEL 6 and 7 are outside support scope. Organizations should deploy the applicable vendor kernel updates or move to a current stable kernel release.
