{"id":"CVE-2026-126957","aliases":["EUVD-2026-124154","GHSA-cvv6-5f6x-87qf"],"status":"published","title":"ICMPv4 Record Route / Timestamp option: stack OOB read via ptr underflow in icmpv4.c","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.","severity":{"version":"4.0","score":6.9,"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00251,"percentile":0.16649,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-125","CWE-191","CWE-200"],"published":"2026-11-12T02:23:44Z","modified":"2026-11-12T10:45:32Z","products":[{"vendor":"zephyrproject-rtos","product":"zephyr"}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-cvv6-5f6x-87qf","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126957.json","tags":["advisory"]},{"url":"https://github.com/zephyrproject-rtos/zephyr","tags":["package"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-126957","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-126957","title":"ICMPv4 Record Route / Timestamp option: stack OOB read via ptr underflow in icmpv4.c","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.","status":"published","published":"2026-11-12T02:23:44.385Z","modified":"2026-11-12T02:23:44.385Z","cvss":[{"version":"4.0","score":6.9,"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","level":"medium","assessor":"cna"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-125","CWE-191","CWE-200"],"updated_at":"2026-11-12T03:36:44.363384Z"}],"euvd":[{"id":"EUVD-2026-124154","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.","status":"published","published":"2026-11-12T02:23:44Z","modified":"2026-11-12T02:23:44Z","cvss":[{"version":"4.0","score":6.9,"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","level":"medium"}],"updated_at":"2026-11-12T03:31:38.547319Z"}],"nvd":[{"id":"CVE-2026-126957","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.","status":"published","published":"2026-11-12T03:17:11.617Z","modified":"2026-11-12T20:28:31.817Z","cvss":[{"version":"4.0","score":6.9,"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-125","CWE-191","CWE-200"],"updated_at":"2026-11-12T06:28:14.789027Z"}],"osv":[{"id":"CVE-2026-126957","title":"ICMPv4 Record Route / Timestamp option: stack OOB read via ptr underflow in icmpv4.c","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.","status":"published","published":"2026-11-12T02:23:44.385Z","modified":"2026-11-12T10:45:32.505099898Z","cvss":[{"version":"4.0","score":6.9,"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","level":"medium"}],"cwes":["CWE-125","CWE-191","CWE-200"],"updated_at":"2026-11-12T11:17:24.122775Z"}]}}