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.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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-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.
Open ATT&CK lookupExecution 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 lookupCVE-2021-1335 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- 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
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.
CVSS vector scores
1 official scoreWe 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.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H1.25.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.2HighVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20210203 Cisco Small Business RV Series Routers Management Interface Remote Command Execution and Denial of Service VulnerabilitiesCVE reference · vendor-advisory, x_refsource_CISCO
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
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.
