Security readout for executives and security teams
Plain-English summary
This is a critical flaw in older Cisco Small Business RV routers. An unauthenticated remote attacker could take over an affected device or force it to restart by abusing its UPnP service. Cisco states it has not released software updates for this vulnerability, so affected devices should be treated as high-risk infrastructure.
Executive priority
Treat this as urgent if any named routers remain in use. The impact is full device compromise or outage, and the provided vendor source says no Cisco software update is available.
Technical view
CVE-2021-34730 affects Cisco RV110W, RV130, RV130W, and RV215W routers. The UPnP service improperly validates incoming traffic, enabling unauthenticated remote arbitrary code execution as root or device reload. The CVSS 3.1 score is 9.8 with network attack vector, low complexity, no privileges, and no user interaction.
Likely exposure
Exposure is limited to the named Cisco Small Business RV router models running affected firmware, especially where the UPnP service is reachable from untrusted networks. The source bundle does not provide exact affected version ranges or CPEs.
Exploitation context
The bundle describes remote unauthenticated exploitation by crafted UPnP traffic. It does not cite active exploitation, and the CVE is not marked CISA KEV in the provided data.
Researcher notes
Evidence supports unauthenticated network RCE and DoS through UPnP input validation failure, mapped to CWE-121. The provided data lacks affected firmware version detail, exploit-in-the-wild confirmation, and vendor-provided fixed releases.
Mitigation direction
- Check Cisco’s advisory for current vendor guidance and lifecycle status.
- Do not assume a patch exists; Cisco says no software updates were released.
- Inventory and prioritize replacement or isolation of affected router models.
- Restrict untrusted network access to router management and UPnP-related services.
Validation and detection
- Identify any RV110W, RV130, RV130W, or RV215W routers in the environment.
- Confirm whether UPnP exposure exists using approved asset and firewall data.
- Review device stability records for unexplained reloads or outages.
- Compare device status against Cisco’s advisory and internal lifecycle policy.
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-2021-34730 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
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/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:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20210818 Cisco Small Business RV110W, RV130, RV130W, and RV215W Routers Remote Command Execution and Denial of Service 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.
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.