CVE-2021-4105
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 · uneditedImproper Handling of Parameters vulnerability in BG-TEK COSLAT Firewall allows Remote Code Inclusion. This issue affects COSLAT Firewall: from 5.24.0.R.20180630 before 5.24.0.R.20210727.
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 BG-TEK COSLAT Firewall contains an improper handling of parameters vulnerability that enables Remote Code Inclusion (RCI). This allows an unauthenticated remote attacker to inject and execute arbitrary code on the affected firewall system through manipulated parameters. The vulnerability affects versions from 5.24.0.R.20180630 up to but not including 5.24.0.R.20210727.
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>= 5.24.0.r.20180630, < 5.24.0.r.20210727>= 5.24.0.r.20180630, < 5.24.0.r.20210727>= 5.24.0.r.20180630, < 5.24.0.r.20210727>= 5.24.0.r.20180630, < 5.24.0.r.20210727>= 5.24.0.r.20180630, < 5.24.0.r.20210727>= 5.24.0.r.20180630, < 5.24.0.r.20210727>= 5.24.0.r.20180630, < 5.24.0.r.20210727>= 5.24.0.r.20180630, < 5.24.0.r.20210727CVSS 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
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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 checksWork through these to decide whether this CVE applies to you.
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Identify firewall model and firmware versionAccess the firewall administrative interface or CLI and navigate to System Information or Firmware Status to retrieve the exact model number (e.g., Bx5s1d3, Rm1ds1000) and firmware version stringAffected if The model matches any of the affected product lines AND the firmware version falls within the range >= 5.24.0.R.20180630 and < 5.24.0.R.20210727
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Confirm remote management interface is accessibleCheck if the firewall web management port (typically 443, 8080, or vendor-default) is exposed to untrusted networks by reviewing firewall rules, NAT configurations, or network scansAffected if The administrative or web-based management interface is reachable from external or untrusted networks without VPN or IP restrictions
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Inspect web server logs for RCI indicatorsReview firewall web server access logs for unusual query parameters, such as those containing file paths (e.g., ../), file extensions (e.g., .php, .sh, .exe), or suspicious base64-encoded strings in URL parametersAffected if Logs contain requests with manipulated parameters that attempt to include or execute remote code, especially in unauthenticated contexts
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Check for unauthorized code execution artifactsExamine the filesystem for unexpected scripts, shells, or executables in web-accessible directories (/www, /cgi-bin, /tmp) and review running processes for unfamiliar binariesAffected if Unexpected files or processes exist that were not installed by administrators, indicating possible exploitation
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Review network connections and servicesUse netstat or equivalent to list active network connections, particularly listening on unusual ports or establishing outbound connections to unknown external addressesAffected if The firewall has active connections to suspicious external IPs or is listening on ports not configured by the administrator
A defender is affected if the COSLAT Firewall model and firmware version fall within 5.24.0.R.20180630 through 5.24.0.R.20210726 and the management interface is exposed to untrusted networks, or if logs or system artifacts show evidence of RCI exploitation.
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.
dbcve · scoped5.24.0.r.20210727
Upgrade the COSLAT Firewall to version 5.24.0.R.20210727 or later to obtain the patched firmware. If immediate patching is not possible, restrict network access to the firewall management interfaces and implement WAF rules to detect and block malicious parameter payloads.
5.24.0.r.20210727
- Download firmware version 5.24.0.r.20210727 or later from the official Coslat support portal
- Access the Coslat COSLAT Firewall administrative interface
- Navigate to the firmware upgrade section (typically System > Firmware Update or Maintenance > Upgrade)
- Upload the firmware file and initiate the upgrade process
- Wait for the upgrade to complete and verify the device reboots successfully
- Confirm the firmware version is now 5.24.0.r.20210727 or later
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation4.0 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 $4,448.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-4105 — 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-2021-4105 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
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