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B426 FirmwareOperating system · Bosch

CVE-2021-23845

HIGH · 8.8 CVSS v3.1 Published 2021-06-18
Fix available
A fix is available. Upgrade to 03.08 / 03.10 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

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 · unedited
This vulnerability could allow an attacker to hijack a session while a user is logged in the configuration web page. This vulnerability was discovered by a security researcher in B426 and found during internal product tests in B426-CN/B429-CN, and B426-M and has been fixed already starting from version 3.08 on, which was released on June 2019.

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 confidence

This is a session hijacking vulnerability in the configuration web interface of specific network hardware devices (B426, B429-CN, B426-M). An attacker can intercept or steal session credentials/tokens to impersonate a logged-in user and perform administrative actions.

MitigationUpgrade to version 3.08 or later (released June 2019). If upgrading is not possible, implement network segmentation to restrict access to the configuration web page and enable session monitoring for anomalies.

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 data
B426 FirmwareOperating system
Affected:< 03.08
B426 Cn FirmwareOperating system
Affected:< 03.08
B429 Cn FirmwareOperating system
Affected:< 03.08
B426 M FirmwareOperating system
Affected:< 03.10

CVSS 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
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify the device model
    Access the device web interface or CLI and retrieve the model number (B426, B429-CN, or B426-M) from the system information or device status page
    Affected if The device is not one of these three models (B426, B429-CN, B426-M)
  2. Retrieve the firmware version
    In the web interface, navigate to the System or About page to view the installed firmware version. Alternatively, use the CLI command specified in the device documentation (often 'show version' or similar)
    Affected if The firmware version is below 03.08 for B426 or B429-CN, or below 03.10 for B426-M
  3. Confirm the web configuration interface is enabled
    Verify that the embedded web server for device configuration is active by attempting to access the device IP on ports 80 or 443 via HTTP/HTTPS
    Affected if The web configuration interface is accessible and the device model/version is in the affected range
  4. Check session token configuration
    Log into the web interface and inspect browser developer tools (Application/Storage tab) to verify if session cookies or tokens are set with secure flags, or check if the HTTP response headers include secure session handling
    Affected if Session tokens lack secure flags (HttpOnly, Secure) and the device firmware is in the vulnerable version range

The environment is affected if the device is a Bosch B426, B429-CN, or B426-M running firmware below 03.08 (or 03.10 for B426-M) and the configuration web interface is accessible.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Upgrade available Upgrade to 03.08 / 03.10 or later
Fixed in 03.0803.10
Interim mitigation

Upgrade to version 3.08 or later (released June 2019). If upgrading is not possible, implement network segmentation to restrict access to the configuration web page and enable session monitoring for anomalies.

Recommended fix High confidence

Firmware 03.08 or later for B426/B426-CN/B429-CN; Firmware 03.10 or later for B426-M

  1. 1. Identify the exact model number of the Bosch device (B426, B426-CN, B429-CN, or B426-M)
  2. 2. Check the current firmware version installed on the device through the configuration web interface
  3. 3. For B426, B426-CN, or B429-CN models: Download firmware version 03.08 or later from the official Bosch download portal (psirt.bosch.com or boschsecurity.com)
  4. 4. For B426-M model: Download firmware version 03.10 or later from the official Bosch download portal
  5. 5. Access the device's web-based configuration interface and navigate to the firmware update section
  6. 6. Upload and apply the downloaded firmware file following the vendor's documented upgrade procedure
  7. 7. After the device reboots, verify the new firmware version is correctly installed
  8. 8. Test that the configuration web page functions normally and the session management works correctly

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in B426 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,600
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-23845 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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