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CVE Record

CVE-2021-1335: Cisco Small Business RV Series Routers Management Interface Remote Command Execution and Denial of Service Vulnerabilities

Multiple 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.

HighCVSS 7.2Not KEV-listedUpdated
Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This issue affects several Cisco Small Business RV routers. An attacker who already has administrator credentials could abuse the web management interface to run commands as root or crash the device. The business risk is serious, but the credential requirement reduces immediate likelihood compared with unauthenticated edge-device flaws.

Executive priority

Treat this as a high-priority edge-device hygiene issue. It is not documented here as actively exploited, but compromised admin credentials could turn the router into a root-level control point or cause outages.

Technical view

CVE-2021-1335 is a high-severity Cisco RV-series management-interface flaw caused by improper validation of user-supplied input, mapped to CWE-121. Crafted HTTP requests from an authenticated remote administrator could execute arbitrary code as root or trigger device reload and denial of service. CVSS v3.1 score is 7.2.

Likely exposure

Exposure is likely limited to environments using Cisco RV016, RV042, RV042G, RV082, RV320, or RV325 routers with reachable web-based management interfaces. Risk increases where administrator credentials are shared, weak, reused, or exposed through phishing, password reuse, or prior compromise.

Exploitation context

The provided sources do not show CISA KEV listing or active exploitation evidence. Exploitation requires valid administrator credentials on the affected device. The cited impact is still severe because successful exploitation can provide root-level code execution or cause router downtime.

Researcher notes

The supplied data does not provide exact affected firmware ranges, fixed versions, or proof-of-concept status. Analysis should stay anchored to Cisco’s advisory and CVE records. Validation should focus on model inventory, management-plane exposure, firmware status, and administrator credential control.

Mitigation direction

  • Check Cisco’s advisory for affected firmware and official remediation guidance.
  • Update affected RV router firmware if Cisco lists a fixed release for your model.
  • Restrict web management access to trusted administrative networks only.
  • Review and rotate router administrator credentials where exposure is possible.
  • Disable unnecessary remote management where operationally feasible.

Validation and detection

  • Inventory Cisco RV016, RV042, RV042G, RV082, RV320, and RV325 routers.
  • Confirm each device firmware against Cisco’s advisory and current vendor guidance.
  • Verify management interfaces are not exposed to untrusted networks.
  • Review administrator account usage, credential age, and access logs.
  • Test that management access is limited to approved administrative paths.
Prepared
Confidence
medium
Sources
3

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-121: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2021-1335 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.2 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
2Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.2CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H1.25.9Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

7.2High
CVSS 3.1 vector shape for CVE-2021-1335Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone
Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
CiscoCisco Small Business RV Series Router Firmwaren/aListed
Weakness

CWE details

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-121 · source CWE mapping

Stack-based Buffer Overflow

Stack-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.