Security readout for executives and security teams
Plain-English summary
This flaw affects several Cisco Small Business RV routers. An attacker who already has valid administrator credentials could use the web management interface to run code as root or force the device to restart. The business risk is disruption or full router compromise, especially where these devices support branch or small-office connectivity.
Executive priority
Prioritize remediation for internet-facing, branch-office, or operationally critical routers. The attacker needs administrator credentials, which lowers broad opportunistic risk, but successful exploitation can fully compromise routing infrastructure or disrupt service. Lack of version detail in the source bundle makes inventory validation the immediate first step.
Technical view
CVE-2021-1336 is a high-severity authenticated remote command execution and denial-of-service issue in the web-based management interface for Cisco RV016, RV042, RV042G, RV082, RV320, and RV325 routers. Cisco attributes it to improper validation of user-supplied input. Successful exploitation can execute arbitrary code as root or reload the device.
Likely exposure
Exposure is limited to affected Cisco Small Business RV Series routers where an attacker can authenticate with administrator credentials to the web management interface. The source bundle does not provide affected firmware version ranges or CPEs, so model and firmware inventory must be checked against Cisco guidance.
Exploitation context
The CVSS vector is network-reachable with low attack complexity, no user interaction, and high privileges required. The source bundle does not show CISA KEV listing or cited evidence of active exploitation. Treat this as serious because successful exploitation can provide root-level control or cause denial of service.
Researcher notes
The source bundle identifies CWE-121 and CVSS 3.1 score 7.2 with PR:H. It does not provide exploit details, fixed firmware versions, or proof of active exploitation. Analysis should remain scoped to authenticated management-interface exposure on the named Cisco RV models.
Mitigation direction
- Identify all affected Cisco RV Series router models in the environment.
- Review Cisco’s advisory for supported fixed firmware or vendor-directed action.
- Restrict web management access to trusted administrative networks only.
- Rotate and review administrator credentials for affected devices.
- Replace unsupported devices if Cisco guidance provides no maintained update path.
Validation and detection
- Confirm whether deployed routers match the affected Cisco RV model list.
- Record firmware versions and compare them with Cisco advisory guidance.
- Verify web management is not exposed beyond intended administrative networks.
- Review device logs for unexpected administrator activity or unexplained reloads.
- Confirm remediation through inventory evidence, not only change tickets.
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-2021-1336 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.