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.
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History
Thu, 12 Nov 2026 02:30:00 +0000
| Type | Values Removed | Values Added |
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| 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. | |
| Title | ICMPv4 Record Route / Timestamp option: stack OOB read via ptr underflow in icmpv4.c | |
| Weaknesses | CWE-125 CWE-191 CWE-200 |
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cvssV3_1
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MITRE
Status: PUBLISHED
Assigner: zephyr
Published:
Updated: 2026-11-12T02:23:44.385Z
Reserved: 2026-11-12T02:06:20.541Z
Link: CVE-2026-126957
Vulnrichment
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NVD
Status : Received
Published: 2026-11-12T03:17:11.617
Modified: 2026-11-12T03:17:11.617
Link: CVE-2026-126957
Redhat
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OpenCVE Enrichment
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