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CVE Record

CVE-2021-1339: 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 flaw affects Cisco Small Business RV-series routers. An attacker who already has valid administrator credentials could abuse the web management interface to run code as root or force the router to reload. Business urgency is highest where these routers protect branch offices, remote sites, or exposed management networks.

Executive priority

Treat as a high-priority edge-device risk, especially for remote offices. It is not unauthenticated, but a compromised admin account could give an attacker root control or disrupt connectivity. Prioritize exposed management interfaces and unsupported devices first.

Technical view

CVE-2021-1339 is an authenticated remote command execution and denial-of-service issue in the web-based management interface. The bundle attributes it to improper validation of user-supplied input and lists CWE-121. Cisco reports possible root-level code execution or device reload via crafted HTTP requests, with CVSS 3.1 score 7.2 and PR:H.

Likely exposure

Exposure is limited to Cisco Small Business RV016, RV042, RV042G, RV082, RV320, and RV325 routers running affected firmware. Risk requires valid administrator credentials, but impact is severe if management access is reachable by untrusted networks or shared admin accounts are compromised.

Exploitation context

The provided sources do not show CISA KEV listing or active exploitation. Exploitation requires authenticated administrator access to the web management interface. The main concern is post-credential-compromise impact: root-level execution or denial of service on small-business edge routers.

Researcher notes

Do not assume active exploitation from this bundle. Validation should focus on product identification, firmware posture, management-plane reachability, and administrator credential exposure. The source data does not provide exploit details or specific fixed versions in the included text.

Mitigation direction

  • Review Cisco advisory for fixed firmware or supported replacement guidance.
  • Apply vendor-recommended firmware updates where available.
  • Restrict router management access to trusted admin networks only.
  • Remove unnecessary internet exposure of web-based management interfaces.
  • Rotate and harden administrator credentials on affected devices.

Validation and detection

  • Inventory RV016, RV042, RV042G, RV082, RV320, and RV325 devices.
  • Compare installed firmware against Cisco advisory guidance.
  • Confirm web management is not reachable from untrusted networks.
  • Review administrator account use for compromise or shared credentials.
  • Document remediation status for each affected router.
Prepared
Confidence
high
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.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2021-1339 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-2021-1339Attack 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.