Security readout for executives and security teams
Plain-English summary
CVE-2021-1155 is a stored cross-site scripting issue in the management interface of several Cisco Small Business RV routers. An attacker must already have valid administrator credentials, but could plant script that runs when another interface user views affected content. Business risk is mainly compromise of browser-session data or trusted admin actions.
Executive priority
Treat this as a moderate, targeted administrative-interface risk. It is not shown as actively exploited and requires admin credentials, but affected routers can sit at sensitive network edges. Prioritize confirmation of device presence, management-plane isolation, and Cisco-supported remediation guidance.
Technical view
Cisco describes multiple CWE-79 stored XSS vulnerabilities caused by insufficient input validation in the web-based management interface of RV110W, RV130, RV130W, and RV215W routers. CVSS 3.1 is 4.8: network reachable, low complexity, high privileges required, user interaction required, changed scope, low confidentiality and integrity impact, no availability impact.
Likely exposure
Exposure is limited to organizations still operating the named Cisco Small Business RV router models and allowing administrative access to the web management interface. The source bundle does not provide affected firmware version ranges, CPEs, or product lifecycle status, so asset inventory and Cisco advisory review are necessary.
Exploitation context
The sources do not show CISA KEV listing or active exploitation. Exploitation requires valid administrator credentials and a victim user interacting with the management interface. The likely attacker profile is someone who already controls or has stolen admin access to an affected router.
Researcher notes
Evidence is sufficient for vulnerability type, affected model names, prerequisites, CVSS, and impact. Evidence is incomplete for exact affected firmware versions, patch availability, exploit publication, and real-world exploitation. Avoid assuming broader Cisco RV exposure beyond the four named models.
Mitigation direction
- Review Cisco’s advisory for fixed firmware, support, or replacement guidance.
- Restrict router management access to trusted admin networks or VPN paths.
- Remove unused administrator accounts and rotate exposed admin credentials.
- Monitor router administration logs for unexpected configuration activity.
- Keep browser access to router administration separate from general web browsing.
Validation and detection
- Inventory RV110W, RV130, RV130W, and RV215W devices in use.
- Check each device’s firmware and support status against Cisco’s advisory.
- Confirm the management interface is not exposed to untrusted networks.
- Review administrator accounts for unnecessary or stale privileged access.
- Look for unexpected stored content or recent admin changes in router settings.
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-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. 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 lookupCVE-2021-1155 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
- Medium
- CVSS
- 4.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
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:R/S:C/C:L/I:L/A:N1.72.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.8MediumVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- 20210113 Cisco Small Business RV110W, RV130, RV130W, and RV215W Routers Management Interface Stored Cross-Site Scripting 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.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.