CVE-2021-1321
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 · uneditedMultiple vulnerabilities in the web-based management interface of Cisco Small Business RV016, RV042, RV042G, RV082, RV320, and RV325 Routers could allow an authenticated, remote attacker to execute arbitrary code or cause an affected device to restart unexpectedly. These vulnerabilities are due to improper validation of user-supplied input in the web-based management interface. An attacker could exploit these vulnerabilities by sending crafted HTTP requests to an affected device. A successful exploit could allow the attacker to execute arbitrary code as the root user on the underlying operating system or cause the device to reload, resulting in a denial of service (DoS) condition. To exploit these vulnerabilities, an attacker would need to have valid administrator credentials on the affected device.
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 · high confidenceMultiple input validation vulnerabilities in the web-based management interface of Cisco Small Business RV series routers allow authenticated attackers with admin credentials to send crafted HTTP requests that can execute arbitrary code as root user on the underlying OS or cause device reload (DoS). The vulnerabilities stem from improper validation of user-supplied input in the web interface.
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<= 4.2.3.14<= 4.2.3.14<= 4.2.3.14<= 4.2.3.14<= 1.5.1.11<= 1.5.1.11CVSS 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
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:H/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 router modelAccess the device status page via the web management interface, or check the physical device label/menu for the model number (RV016, RV042, RV042g, RV082, RV320, or RV325)Affected if Model is one of: RV016, RV042, RV042g, RV082, RV320, or RV325
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Check firmware versionNavigate to the web management interface System Summary or Status page to view the firmware version, or use CLI command 'show version' if availableAffected if Firmware version is <= 4.2.3.14 for RV016/RV042/RV042g/RV082, or <= 1.5.1.11 for RV320/RV325
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Verify web management interface is enabledCheck the device configuration under Administration or Management settings to confirm if the HTTP/HTTPS web interface is enabledAffected if Web-based management interface is enabled (vulnerability is only exploitable through this interface)
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Check network access to management interfaceReview access control lists or firewall rules to determine if the web management interface is accessible from untrusted networksAffected if Web interface is accessible from outside trusted networks (increases exposure to authenticated attackers)
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Review admin accountsCheck the local user database or AAA configuration to list all accounts with administrative privilegesAffected if There are admin accounts, especially weak or default credentials, that could be compromised by attackers
The environment is affected if the router model is one of the vulnerable RV series and the firmware version falls within the affected ranges while the web management interface is 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 dataApply Cisco firmware updates when available; restrict administrative access to the web management interface to trusted networks only; enforce strong administrative credentials to reduce attack surface.
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1321 — 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-2021-1321 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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