Security readout for executives and security teams
Plain-English summary
This flaw affects Cisco RV340, RV340W, RV345, and RV345P VPN routers. Someone who already has valid Administrator credentials and local access could escalate to root on the router operating system. It is serious for affected devices, but the provided sources do not support unauthenticated or active exploitation claims.
Executive priority
Treat this as moderate priority. It is not presented as an unauthenticated internet-scale issue, but root compromise of a VPN router can materially affect network trust. Prioritize confirmation and vendor-guided remediation for any deployed affected models.
Technical view
CVE-2021-1520 is an input sanitization issue in an internal messaging service on Cisco RV340, RV340W, RV345, and RV345P routers. An authenticated local attacker with Administrator credentials could send a crafted request to that service and execute arbitrary OS commands as root. CVSS 3.1 is 6.7 with AV:L/AC:L/PR:H/UI:N.
Likely exposure
Exposure is limited to organizations running the named Cisco Small Business RV Series router firmware on RV340, RV340W, RV345, or RV345P devices. The bundle indicates local attack requirements and valid Administrator credentials; it does not show broad internet-exposed exploitation.
Exploitation context
The source bundle does not identify active exploitation, and CISA KEV status is false. Exploitation requires valid Administrator credentials before abusing the internal service. This is best treated as a post-authentication privilege escalation risk on already-accessible router administration environments.
Researcher notes
Key constraints are local attack vector and high privileges. The provided evidence supports root command execution after Administrator authentication via crafted internal-service messaging. Do not infer remote unauthenticated exploitation, public exploit availability, or specific fixed versions from this bundle alone.
Mitigation direction
- Check Cisco's advisory for fixed firmware or official guidance for affected router models.
- Inventory RV340, RV340W, RV345, and RV345P devices in production and remote sites.
- Restrict Administrator access to trusted personnel and controlled management paths.
- Review Administrator credential hygiene, including shared, stale, or unnecessary accounts.
- Prioritize remediation where router administrators have broad or poorly monitored access.
Validation and detection
- Confirm whether any RV340, RV340W, RV345, or RV345P routers are deployed.
- Compare each device firmware state against Cisco's advisory guidance.
- Review router Administrator accounts for unauthorized or unnecessary access.
- Check administrative logs for unexpected local management activity.
- Document affected devices, remediation status, and any accepted residual risk.
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-123: 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 lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-1520 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
- 6.7 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/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:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H0.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.7MediumVector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20210505 Cisco RV340, RV340W, RV345, and RV345P Dual WAN Gigabit VPN Routers Local Privilege Escalation VulnerabilityCVE 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.
Write-what-where Condition
Write-what-where Condition represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.