VulnerabilityDeferred

CVE-2026-53921

Two independent overflow sites exist in the same call chain, both reachable from the network via a single unauthenticated UDP packet. odhcpd runs as root on OpenWrt; embedded targets often lack stack canaries and ASLR, making code execution realistic.

CRITICAL 9.8EPSS 1.12%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (1.12%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. Prior to version 25.12, odhcpd's DHCPv6 IA response handler writes past the end of a fixed 512-byte stack buffer (pdbuf) when a single DHCPv6 REQUEST carries enough IA options to nearly exhaust the reply space. Two independent overflow sites exist in the same call chain, both reachable from the network via a single unauthenticated UDP packet. odhcpd runs as root on OpenWrt; embedded targets often lack stack canaries and ASLR, making code execution realistic. This issue has been patched in version 25.12.

CVSS 3.1: 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS: 1.12% probability · 66th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Weakness: CWE-121
Source: security-advisories@github.com

EPSS trend

EPSS moved from 0.9% on 24 October 2026 to 1.1% on 26 October 2026.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.