CVE DATABASE / CVE-2021-20090
CVE-2021-20090
Arcadyan Buffalo Firmware Path Traversal Vulnerability
CVSS 9.8 · CRITICAL
⚠ CISA KEV — ACTIVELY EXPLOITED
On the CISA KEV catalog
Confirmed exploited in the wild. Added 2021-11-03.
Federal remediation due 2021-11-17.
Required action: Apply updates per vendor instructions.
Summary
A path traversal vulnerability in the web interfaces of Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 could allow unauthenticated remote attackers to bypass authentication.
CVSS 3.1 breakdown
| Base score | 9.8 (CRITICAL) |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Attack vector | NETWORK |
| Attack complexity | LOW |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity | HIGH |
| Availability | HIGH |
Weakness type (CWE)
Affected products
Buffalo wsr-2533dhpl2-bk firmwareBuffalo wsr-2533dhpl2-bkBuffalo wsr-2533dhp3-bk firmwareBuffalo wsr-2533dhp3-bk
Check this CVE live
Use our free CVE Lookup tool for the latest NVD record, or browse the full CISA KEV catalog.
References
- https://www.kb.cert.org/vuls/id/914124
- https://www.secpod.com/blog/arcadyan-based-routers-and-modems-under-active-exploitation/
- https://www.tenable.com/security/research/tra-2021-13
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20090
Data: NIST NVD + CISA KEV. NVD last modified 2025-11-03. Always verify against the vendor advisory before acting.