CVE-2021-20843: Cross-site script inclusion vulnerability in the Web GUI of RTX830 Rev.15.02.17 and earlier, NVR510 Rev.15.01.18 and earlier, NVR700W…
Noroxi assessment
Priority: Monitor (action score 21/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.69% (FIRST EPSS); higher than 53.3% of all records.
- Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. A user must open a link or visit a page. No special conditions are required; it is repeatable.
- According to the record, no fixed version is available yet.
Low priority for now. Update when a fix is released; follow the vendor's advisory.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
Cross-site script inclusion vulnerability in the Web GUI of RTX830 Rev.15.02.17 and earlier, NVR510 Rev.15.01.18 and earlier, NVR700W Rev.15.00.19 and earlier, and RTX1210 Rev.14.01.38 and earlier allows a remote authenticated attacker to alter the settings of the product via a specially crafted web page.
- Published
- Nov 24, 2021
- Updated
- Jun 16, 2026
- EPSS
- 0.6% · 53th percentile
- CWE
- CWE-829
Report tools
Action score
21
Low priority for now.
- CVSS
- 21 / 40 · 5.4 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.6%
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- No fixed version yet
If any of these changes, we'll tell you in the daily email digest.
Is your version affected? Check itNoroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| yamaha | rtx830 firmware | cpe:2.3:o:yamaha:rtx830_firmware |
| yamaha | rtx830 | cpe:2.3:h:yamaha:rtx830 |
| yamaha | nvr510 firmware | cpe:2.3:o:yamaha:nvr510_firmware |
| yamaha | nvr510 | cpe:2.3:h:yamaha:nvr510 |
| yamaha | nvr700w firmware | cpe:2.3:o:yamaha:nvr700w_firmware |
| yamaha | nvr700w | cpe:2.3:h:yamaha:nvr700w |
| yamaha | rtx1210 firmware | cpe:2.3:o:yamaha:rtx1210_firmware |
| yamaha | rtx1210 | cpe:2.3:h:yamaha:rtx1210 |
| ntt-west | biz box rtx830 firmware | cpe:2.3:o:ntt-west:biz_box_rtx830_firmware |
| ntt-west | biz box rtx830 | cpe:2.3:h:ntt-west:biz_box_rtx830 |
| ntt-west | biz box nvr510 firmware | cpe:2.3:o:ntt-west:biz_box_nvr510_firmware |
| ntt-west | biz box nvr510 | cpe:2.3:h:ntt-west:biz_box_nvr510 |
and 4 more
Versions reported by the vendor
Affected version ranges reported by the assigning authority (jpcert). Independent of NVD's CPE analysis and usually ahead of it.
Yamaha Corporation RTX830, NVR510, NVR700W, RTX1210
- RTX830 Rev.15.02.17 and earlier, NVR510 Rev.15.01.18 and earlier, NVR700W Rev.15.00.19 and earlier, RTX1210 Rev.14.01.38 and earlieraffected
Affected versions · NVD (8)
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- ntt-west biz box nvr510 firmwarebefore 15.01.18
- ntt-west biz box nvr700w firmwareup to 15.00.19 inclusive
- ntt-west biz box rtx1210 firmwareup to 14.01.38 inclusive
- ntt-west biz box rtx830 firmwareup to 15.02.17 inclusive
- yamaha nvr510 firmwareup to 15.01.18 inclusive
- yamaha nvr700w firmwareup to 15.00.19 inclusive
- yamaha rtx1210 firmwareup to 14.01.38 inclusive
- yamaha rtx830 firmwareup to 15.02.17 inclusive
Same product
yamaha: all recordsOther highest-scoring records for the same primary product.
- CVE-2020-5548Yamaha LTE VoIP Router(NVR700W firmware Rev.15.00.15 and earlier), Yamaha Gigabit VoIP Router(NVR510 firmware Rev.15.01.14 and earlier)…30Monitor
- CVE-2021-20844Improper neutralization of HTTP request headers for scripting syntax vulnerability in the Web GUI of RTX830 Rev.15.02.17 and earlier…22Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- A low-privileged account is enough.
- A user must open a link or visit a page.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- low · data can be read
- Integrity
- low · data or configuration can be modified
- Availability
- none
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- Required
- Scope
- Changed
- Confidentiality impact
- Low
- Integrity impact
- Low
- Availability impact
- None
Weakness class (CWE)
CWE-829 · Inclusion of Functionality from Untrusted Control SphereCVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Code InclusionCAPEC-175likelihood: Medium · Very High
- Serialized Data External LinkingCAPEC-201likelihood: High · High
- DTD InjectionCAPEC-228Medium
- Local Code InclusionCAPEC-251Medium
- PHP Local File InclusionCAPEC-252Medium
- Remote Code InclusionCAPEC-253
- Force Use of Corrupted FilesCAPEC-263Medium
- Open-Source Library ManipulationCAPEC-538likelihood: Low · High
ATT&CK techniques
- Process InjectionT1055
- Browser ExtensionsT1176
- Supply Chain Compromise: Software Dependencies and Development ToolsT1195.001
- Server Software Component: IIS ComponentsT1505.004
- Server Software Component: Terminal Services DLLT1505.005
- Hijack Execution Flow: Dynamic Linker HijackingT1574.006
- Hijack Execution Flow: KernelCallbackTableT1574.013
- Reflective Code LoadingT1620
Change log (0)
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
Show all references (3 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.