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VulnerabilityPublished

CVE-2026-126957: zephyrproject-rtos Zephyr · Out-of-bounds Read

Affects zephyrproject-rtos ZephyrSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium.

Data as of 12 Nov 2026, 02:48 UTC

CVSS 3.1 base score
5.3Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (zephyr)CVSS 3.15.3
CNA (zephyr)CVSS 4.06.9
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
zephyrproject-rtosZephyrAffected
  • <=4.4.0
Fixed in–
GitHubZephyrpkg:github/ZephyrOther threatsAffected
  • <=4.4.0
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until a fix is available, consider disabling CONFIG_NET_IPV4_HDR_OPTIONS or CONFIG_NET_IPV4_IGMP if feasible to mitigate exposure. Monitor vendor channels for updates and apply patches promptly once released.

Description

CVE-2026-126957 is an integer underflow vulnerability in Zephyr's IPv4 option handling that allows a remote unauthenticated attacker to read up to 213 bytes of stack memory. The flaw occurs when processing ICMP Echo Requests with IPv4 Record Route or Timestamp options, leading to out-of-bounds reads and information leakage. Devices built with CONFIG_NET_IPV4_HDR_OPTIONS (selected by CONFIG_NET_IPV4_IGMP) and running Zephyr versions up to 4.4.0 are affected. The vulnerability does not cause crashes and can be repeatedly exploited to leak memory contents.

References

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