CVE-2021-23842
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedCommunication to the AMC2 uses a state-of-the-art cryptographic algorithm for symmetric encryption called Blowfish. An attacker could retrieve the key from the firmware to decrypt network traffic between the AMC2 and the host system. Thus, an attacker can exploit this vulnerability to decrypt and modify network traffic, decrypt and further investigate the device\'s firmware file, and change the device configuration. The attacker needs to have access to the local network, typically even the same subnet.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceThe AMC2 access control device uses Blowfish symmetric encryption for communication with the host system. The encryption key is embedded in or recoverable from the device firmware, allowing an attacker with local network access to decrypt traffic, modify communications in transit, extract the firmware for further analysis, and alter device configuration.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE dataall versions= 3.0<= 3.8.0< 4.9.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify AMC2 access control devices on the networkScan your network for devices with the AMC2 product identifier or check your asset inventory for Bosch AMC2 hardware. Use network scanning tools or consult your asset management database.Affected if AMC2 devices are present on the network
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Check Access Management System versionOpen the Bosch Access Management System admin console and navigate to the About or System Information section to view the installed version number.Affected if Version is exactly 3.0
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Check Access Professional Edition versionLaunch the Access Professional Edition software and go to Help > About or System > Version Information to confirm the installed build number.Affected if Version is 3.8.0 or lower
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Check Building Integration System versionAccess the BIS management portal and locate the version information typically found under System Overview or the About page.Affected if Version is below 4.9.1
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Verify Blowfish encryption is in use for AMC2 communicationInspect the AMC2 device configuration or network traffic between the AMC2 and host system to confirm Blowfish encryption is enabled for device communication.Affected if Blowfish encryption is configured for AMC2 host communication
You are affected if you have any AMC2 hardware on your network, or run Access Management System 3.0, Access Professional Edition <= 3.8.0, or Building Integration System < 4.9.1 with AMC2 integration enabled.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data4.9.1
Restrict network access to the AMC2 device through VLAN segmentation or firewall controls; contact vendor for firmware update addressing key exposure; monitor for unauthorized configuration changes.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-23842 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-23842 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data