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CVE-2026-126957 ICMPv4 Record Route / Timestamp option: stack OOB read via ptr underflow in icmpv4.c

6.9 mediumEPSS 0.3%

Medium (6.9) in zephyrproject-rtos zephyr. EPSS 0.3% estimated probability of exploitation activity in the next 30 days.

On this page
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

CVSS 4.0

6.9 medium
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

CVSS 3.1

5.3 medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
EPSS
0.3% estimated probability of exploitation activity in the next 30 days; 17th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
CWEs
CWE-125 Out-of-bounds Read
CWE-191 Integer Underflow (Wrap or Wraparound)
CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
OWASP Top 10
A01:2025 Broken Access Control
Published
Modified
Assigned by
zephyr (CNA)
NVD analysis
Awaiting analysis
Record from
the NVD, synced

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Affected

Attack patterns (CAPEC)

  • CAPEC-540 Overread Buffers Likelihood: Low · Severity: High

The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits. More on the page of CWE-200 (59).

References

Check your stackJSON