CVE-2026-64024

In the Linux kernel, the following vulnerability has been resolved: tcp: fix stale per-CPU tcp_tw_isn leak enabling ISN prediction Blamed commit moved the TIME_WAIT-derived ISN from the skb control block to a per-CPU variable, assuming the value would always be consumed by tcp_conn_request() for the same packet that wrote it. That assumption is violated by multiple drop paths between the producer (__this_cpu_write(tcp_tw_isn, isn) in tcp_v{4,6}_rcv()) and the consumer (tcp_conn_request()): - min_ttl / min_hopcount check - xfrm policy check - tcp_inbound_hash() MD5/AO mismatch - tcp_filter() eBPF/SO_ATTACH_FILTER drop - th->syn && th->fin discard in tcp_rcv_state_process() TCP_LISTEN - psp_sk_rx_policy_check() in tcp_v{4,6}_do_rcv() - tcp_checksum_complete() in tcp_v{4,6}_do_rcv() - tcp_v{4,6}_cookie_check() returning NULL When a packet is dropped on any of these paths, tcp_tw_isn is left set. The next SYN processed on the same CPU then consumes the non zero value in tcp_conn_request(), receiving a potentially predictable ISN. This patch moves back tcp_tw_isn to skb->cb[], getting rid of the per-cpu variable. Note that tcp_v{4,6}_fill_cb() do not set it. Very litle impact on overall code size/complexity: $ scripts/bloat-o-meter -t vmlinux.old vmlinux.new add/remove: 0/0 grow/shrink: 2/1 up/down: 8/-15 (-7) Function old new delta tcp_v6_rcv 3038 3042 +4 tcp_v4_rcv 3035 3039 +4 tcp_conn_request 2938 2923 -15 Total: Before=24436060, After=24436053, chg -0.00%
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:*

History

29 Oct 2026, 15:55

Type Values Removed Values Added
References () https://git.kernel.org/stable/c/8bb6aa419b142dcc2680177ecc39c4c38db7fc16 - () https://git.kernel.org/stable/c/8bb6aa419b142dcc2680177ecc39c4c38db7fc16 - Patch

21 Oct 2026, 13:19

Type Values Removed Values Added
References
  • () https://git.kernel.org/stable/c/8bb6aa419b142dcc2680177ecc39c4c38db7fc16 -

19 Oct 2026, 21:17

Type Values Removed Values Added
CWE CWE-362

13 Oct 2026, 15:00

Type Values Removed Values Added
CWE CWE-401
References () https://git.kernel.org/stable/c/1bbf0ced1d9db73ac7893c2187f3459288603e0d - () https://git.kernel.org/stable/c/1bbf0ced1d9db73ac7893c2187f3459288603e0d - Patch
References () https://git.kernel.org/stable/c/4affe063fa56c880cbea8d0bfded0bb80751579d - () https://git.kernel.org/stable/c/4affe063fa56c880cbea8d0bfded0bb80751579d - Patch
References () https://git.kernel.org/stable/c/e47f7060eaf60894e3e4d0e3c4fe6e1f2eacfbdd - () https://git.kernel.org/stable/c/e47f7060eaf60894e3e4d0e3c4fe6e1f2eacfbdd - Patch
CPE cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
First Time Linux
Linux linux Kernel

Information

Published : 2026-07-19 16:17

Updated : 2026-10-29 15:55


NVD link : CVE-2026-64024

Mitre link : CVE-2026-64024

CVE.ORG link : CVE-2026-64024


JSON object : View

Products Affected

linux

  • linux_kernel
CWE
CWE-401

Missing Release of Memory after Effective Lifetime

CWE-362

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')