What is CVE-2021-37604?

CVE-2021-37604 is a high-severity vulnerability in Microchip Miwi, classified under Always-Incorrect Control Flow Implementation. CVSS score: 7.5/10. Published 2021-08-05.

How severe is CVE-2021-37604?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2021-37604 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Microchip Miwi

CVE-2021-37604

In version 6.5 of Microchip MiWi software and all previous versions including legacy products, there is a possibility of frame counters being validated/updated prior to the message authentication. With this vulnerability in place, an attacker may increment the incoming frame counter values by injecting messages with a sufficiently large frame counter value and invalid payload. This results in denial of service/valid packets in the network. There is also a possibility of a replay attack in the stack.

Published 2021-08-05 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.012 (67.6th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 68th percentile — 67.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000

Affected products

Microchip Miwi — versions 6.5

Weakness classification (CWE)

CWE-670 — Always-Incorrect Control Flow Implementation

Public proof-of-concept exploits

References

www.microchip.com/product-change-notifications/ (Vendor Advisory)
www.microchip.com/en-us/products/wireless-connectivity/sub-ghz/miwi-protocol (Vendor Advisory)
ww1.microchip.com/downloads/en/DeviceDoc/asf-release-notes-3.50.0.100-readme.pdf (Release Notes, Vendor Advisory)
www.microchip.com/en-us/development-tools-tools-and-software/libraries-code-exa… (Vendor Advisory)
www.microchip.com/en-us/products/wireless-connectivity/software-vulnerability-r… (Vendor Advisory)

Frequently asked questions

What is CVE-2021-37604?: CVE-2021-37604 is a high-severity vulnerability in Microchip Miwi, classified under Always-Incorrect Control Flow Implementation. CVSS score: 7.5/10. Published 2021-08-05.
How severe is CVE-2021-37604?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2021-37604 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.