CVEs / CVE-2021-20090
CVE-2021-20090: Arcadyan Buffalo Firmware Path Traversal Vulnerability
- Known exploited in the CISA KEV catalog since 3 Nov 2021
- critical 9.8 CVSS 3.1 (NVD)
- EPSS 99.9% chance of exploitation in the next 30 days, higher than 99% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
Arcadyan Buffalo firmware contains a path traversal vulnerability that could allow unauthenticated, remote attackers to bypass authentication and access sensitive information. This vulnerability affects multiple routers across several different vendors.
Description
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.
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| n/a Buffalo WSR-2533DHPL2, Buffalo WSR-2533DHP3 | WSR-2533DHPL2 <=1.02, WSR-2533DHP3 <= 1.24 | — |
Exploitation
| In CISA KEV since | 3 Nov 2021 |
|---|---|
| Due date for US federal agencies | 17 Nov 2021 |
| Used in ransomware campaigns | Unknown |
| Required action | Apply updates per vendor instructions. |
Severity
| CVSS 3.1 | 9.8 criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HScored by NVD |
|---|---|
| Weakness | CWE-22 |
References
- CVE-2021-20090 on NVD
- CVE-2021-20090 in the CISA KEV catalog
- https://www.kb.cert.org/vuls/id/914124 Third Party Advisory, US Government Resource
- https://www.secpod.com/blog/arcadyan-based-routers-and-modems-under-active-exploitation/ Exploit, Third Party Advisory
- https://www.tenable.com/security/research/tra-2021-13 Exploit, Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20090 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.