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Vulnerabilities

Vulnerability · CVE-2021-20090

Arcadyan Buffalo Firmware Path Traversal Vulnerability

Published Apr 29, 2021 · catalog updated Jun 16, 2026 · Arcadyan Buffalo Firmware

Patch now

CVE-2021-20090 is in the CISA known-exploited catalog, due Nov 17, 2021. Confirm Arcadyan Buffalo Firmware against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
Critical9.8
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
99.98%
Remediation
Remediation guidance
Affected products
cpe buffalo/wsr-2533dhp3-bk firmware · cpe buffalo/wsr-2533dhpl2-bk firmware · vendor Arcadyan Buffalo Firmware

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. VulnCheck canary evidence.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe buffalo/wsr-2533dhp3-bk firmwareversion unspecified
  • cpe buffalo/wsr-2533dhpl2-bk firmwareversion unspecified
  • vendor Arcadyan Buffalo Firmwareversion unspecified

How to fix CVE-2021-20090

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2021-20090 is in the CISA known-exploited catalog, due Nov 17, 2021. Confirm Arcadyan Buffalo Firmware against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Affected version ranges are not on this record. Apply updates per vendor instructions.

What should an analyst verify?

CWE-22: Path Traversal. EPSS 99.98%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 29, 2021 · Catalog

    Detected

    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.

  2. Nov 3, 2021 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Nov 17, 2021 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    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.

Sources

  • CISA KEVConfirmed exploitationCVE-2021-20090

    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.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2021-20090

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2021-20090

    30-day exploitation probability 100.0%

    first.org
  • NIST NVDVulnerability recordCVE-2021-20090

    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.

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2021-20090

    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.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.