{"affected":[{"defaultStatus":"unaffected","packageName":"Zephyr","product":"Zephyr","source":"CNA: zephyr","vendor":"zephyrproject-rtos","versions":[{"lessThanOrEqual":"4.4.0","status":"affected","version":"*","versionType":"git"}]}],"cveId":"CVE-2026-126957","cwes":["CWE-125","CWE-191","CWE-200"],"description":"An integer underflow in Zephyr's IPv4 option handling allows a remote, unauthenticated attacker to read stack memory. When replying to an ICMP Echo Request that carries an IPv4 Record Route or Timestamp option, icmpv4_update_record_route() and icmpv4_update_time_stamp() in subsys/net/ip/icmpv4.c compute the length of the already recorded data as ptr - ptr_offset in uint8_t arithmetic. The attacker-controlled Pointer field is checked against the option length but not against the RFC 791 minimum (4 for Record Route, 5 for Timestamp), so a smaller value wraps the length to up to 252 bytes. net_pkt_write() then reads past the 40-byte opt_data stack buffer and up to 213 bytes of stack memory, which can include stack and heap pointers, are returned in the ICMP Echo Reply. A single packet triggers the leak and the device does not crash, so it can be repeated. Devices built with CONFIG_NET_IPV4_HDR_OPTIONS, which CONFIG_NET_IPV4_IGMP selects, are affected.","epss":null,"exploits":[],"kev":null,"metrics":[{"score":5.3,"severity":"medium","source":"CNA: zephyr","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","version":"3.1"},{"score":6.9,"severity":"medium","source":"CNA: zephyr","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N","version":"4.0"}],"modifiedAt":1794450224385,"publishedAt":1794450224385,"references":[{"source":"CNA: zephyr","tags":[],"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-cvv6-5f6x-87qf"}],"remediation":[],"revision":"daf6c63db62dadd7814bad80852334a1903cd39d911a8ca8d7bd04963925afae","sources":[{"modifiedAt":1794450224385,"name":"CNA: zephyr","retrievedAt":1794452949620,"url":"https://www.cve.org/CVERecord?id=CVE-2026-126957"}],"ssvc":null,"status":"published","title":"ICMPv4 Record Route / Timestamp option: stack OOB read via ptr underflow in icmpv4.c","updatedAt":1794452949620}