CVE-2026-19735: zephyr 3.7.0 through 4.4.2

Affected technology

zephyr · 3.7.0 through 4.4.2
zephyrproject

Component: Not specified by the source
Function: tcp_init_isn, tcpv4_init_isn, tcpv6_init_isn, of
File: subsys/net/ip/tcp.c

Attack conditions (Vendor/CNA, CVSS 3.1): Network (remote) · No privileges required · No user interaction required

What an attacker can do

An off-path attacker can compute the hash term offline for any four-tuple and recover the shared time offset from a single observed ISN, after which the ISN the device will pick for other four-tuples is predictable. Vendor/CNA’s CVSS 3.1 assessment (base score 4.8/10) rates confidentiality and integrity impact as low; availability impact as none.