CVE-2021-25664

8.7 highEPSS 1.9%

High (8.7) in siemens. EPSS 1.9% chance of exploitation in the next 30 days.

A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic R20-11 (All versions < V2303), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.4), Nucleus ReadyStart V4 (All versions < V4.1.0), Nucleus Source Code (All versions including affected IPv6 stack). The function that processes the Hop-by-Hop extension header in IPv6 packets and its options lacks any checks against the length field of the header, allowing attackers to put the function into an infinite loop by supplying arbitrary length values.

Severity

CVSS 4.0

8.7 high

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS 3.1

7.5 high

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 1.9% chance of exploitation in the next 30 days; higher than 79% of CVEs (scores of 2026-10-31)
CWE: CWE-835
Published: 2021-04-22
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

siemens:capital_vstar
siemens:nucleus_net
siemens:nucleus_readystart_v3
siemens:nucleus_readystart_v4
siemens:nucleus_source_code

References

Check your stack JSON