CVE-2021-27252
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 · uneditedThis vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of NETGEAR R7800 firmware version 1.0.2.76. Authentication is not required to exploit this vulnerability. The specific flaw exists within the handling of the vendor_specific DHCP opcode. The issue results from the lack of proper validation of a user-supplied string before using it to execute a system call. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-12216.
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 analysisUser input reaches a shell or system command without being fully separated from the command itself, so an attacker can append their own instructions. Because these run with the application's privileges, it often means full control of the host. The lasting fix is to avoid the shell entirely — call APIs directly and pass arguments as data, never as concatenated strings.
General guidance for the os command injection class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →
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< 5.10.0.5< 5.10.0.5< 1.0.1.60< 1.0.1.98< 1.0.1.98< 1.0.0.134< 1.0.2.158< 1.0.0.134CVSS 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
- Adjacent
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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 · scoped1.0.0.1341.0.1.601.0.1.98
Firmware version 5.10.0.5 for Br200/Br500; 1.0.1.60 for D7800; 1.0.1.98 for Ex6100v2/Ex6150; 1.0.0.134 for Ex6250/Ex6400v2; 1.0.2.158 for Ex6400
- Identify the exact NETGEAR device model from the affected list (Br200, Br500, D7800, Ex6100v2, Ex6150, Ex6250, Ex6400, or Ex6400v2)
- Navigate to the NETGEAR support website and download the firmware update for your specific model
- Locate the firmware version that addresses the vulnerability: Br200/Br500 need 5.10.0.5, D7800 needs 1.0.1.60, Ex6100v2/Ex6150 need 1.0.1.98, Ex6250/Ex6400v2 need 1.0.0.134, Ex6400 needs 1.0.2.158
- Access the device administrative web interface or use the NETGEAR Nighthawk/Orbi mobile app
- Locate the firmware update section (typically under Administration > Firmware Update)
- Upload and apply the downloaded firmware file
- Wait for the device to complete the update process and reboot
- Verify the new firmware version is installed and matches the fixed release
Generated from the published advisory — verify against the referenced sources before acting.
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Free · runs locallyCheck whether your project pulls in CVE-2021-27252 — 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-2021-27252 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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- Version or environment caveats, and links to real fixes
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