CVE-2021-37605Network attack vector

Unauthenticated message forgery via truncated MIC validation

Published Aug 5, 2021 · Updated Aug 4, 2024

Improper message authentication in Microchip MiWi 6.5 and earlier allows remote attackers to forge network messages by brute force. The validate_mic() function in mimac_at86rf.c compares only two of the four Message Integrity Check bytes, reducing the effective tag to 16 bits. Exploitation requires radio reachability to the target's IEEE 802.15.4 network and repeated crafted frames; the documented consequence is unauthorized message acceptance.

CVSS severity7.5
High
EPSS probability1.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper message authentication in Microchip MiWi 6.5 and earlier allows remote attackers to forge network messages by brute force. The validate_mic() function in mimac_at86rf.c compares only two of the four Message Integrity Check bytes, reducing the effective tag to 16 bits. Exploitation requires radio reachability to the target's IEEE 802.15.4 network and repeated crafted frames; the documented consequence is unauthorized message acceptance.

The record

CVE
CVE-2021-37605
Published
Aug 5, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-670
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 5, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-670Always-Incorrect Control Flow Implementation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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