Security readout for executives and security teams
Plain-English summary
This issue affects the management interface of several Cisco Small Business RV routers. An attacker who already has administrator credentials could store script content that runs in another interface user's browser, potentially exposing browser-based information tied to that router session.
Executive priority
Handle this as a controlled remediation item, not an emergency, unless affected router management interfaces are broadly exposed or administrator credentials are poorly governed. The business risk is session-level compromise of router administration rather than unauthenticated takeover.
Technical view
CVE-2021-1156 is a stored XSS flaw caused by insufficient input validation in Cisco RV110W, RV130, RV130W, and RV215W web management interfaces. Exploitation is network reachable but requires administrator privileges and user interaction. Successful exploitation can execute script in the interface context or access sensitive browser-based information.
Likely exposure
Exposure is most likely in environments still operating Cisco RV110W, RV130, RV130W, or RV215W routers with the web management interface accessible to administrators. Risk increases where admin accounts are shared, weakly controlled, or the management interface is reachable from untrusted networks.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. The attacker must have valid administrator credentials and convince or wait for a user of the affected interface to encounter the stored script condition.
Researcher notes
CVSS v3.1 is 4.8: AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N. CWE-79 applies. The evidence bundle does not provide exact affected firmware versions, CPEs, fixed releases, or workaround details beyond the Cisco advisory reference.
Mitigation direction
- Check the Cisco advisory for affected firmware and vendor-supported fixes or workarounds.
- Restrict router management interfaces to trusted administrative networks only.
- Review and reduce administrator accounts on affected routers.
- Use unique, controlled administrator credentials for each device.
- Plan replacement if affected devices are unsupported by current Cisco guidance.
Validation and detection
- Inventory Cisco RV110W, RV130, RV130W, and RV215W routers in the environment.
- Confirm each device firmware against Cisco advisory guidance.
- Verify the management interface is not reachable from untrusted networks.
- Review administrator account lists for unnecessary or shared access.
- Check router management logs for unexpected administrative activity.
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-2021-1156 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.
