CVE-2021-23842

Traffic decryption via firmware-embedded Blowfish key

Published Jan 19, 2022 · Updated Sep 16, 2024

Hard-coded cryptographic key use in Bosch AMC2 communications allows attackers to decrypt controller traffic and firmware. The AMC2 firmware embeds the Blowfish key used between the controller and host, allowing the same key to decrypt captured traffic and firmware files. Reachability requires local-network access, typically on the same subnet; Bosch reports that traffic modification can change device configuration.

CVSS severity5.7
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Hard-coded cryptographic key use in Bosch AMC2 communications allows attackers to decrypt controller traffic and firmware. The AMC2 firmware embeds the Blowfish key used between the controller and host, allowing the same key to decrypt captured traffic and firmware files. Reachability requires local-network access, typically on the same subnet; Bosch reports that traffic modification can change device configuration.

The record

CVE
CVE-2021-23842
Published
Jan 19, 2022
Updated
Sep 16, 2024
Vendor
Bosch Security Systems B.V.
Product
Access Management System (AMS)
Classifications
CWE-321, T1557
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 19, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <4.0

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Bosch Security Systems B.V. · Access Management System (AMS)version=unspecified <4.0
Bosch Security Systems B.V. · Access Professional Edition (APE)version=unspecified <=3.8.x
Bosch Security Systems B.V. · Building Integration System (BIS)version=unspecified <4.9.1
Bosch Security Systems B.V. · Access Modular Controller (AMC2)version=all

Published CVSS scores

5.7Robert Bosch GmbHCVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
7.1NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
3.6NIST NVDAV:L/AC:L/Au:N/C:P/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-321Use of Hard-coded Cryptographic Key
T1557Adversary-in-the-Middle

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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