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.
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-2021-1339 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.
