An integer underflow in Zephyr's IPv4 option handling allows a remote, unauthenticated attacker to read stack memory.
CVE-2026-126957
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, icmpv4updaterecordroute() and icmpv4updatetimestamp() in subsys/net/ip/icmpv4.c compute the length of the already recorded data as ptr - ptroffset in uint8t 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. netpktwrite() then reads past the 40-byte optdata 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 CONFIGNETIPV4HDROPTIONS, which CONFIGNETIPV4IGMP selects, are affected.
Assessment
- CVSS
- 6.9 (v4.0)
- Severity
- Medium
- Known exploited
- Not listed in CISA KEV
- Exploit availability
- Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
- Published
- 12 November 2026
- Last updated
- 12 November 2026
- Affected
- zephyrproject-rtos · Zephyr
- Assigner
- zephyr
CVSS vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
At the source
References
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