Critical 9.8Known exploited (CISA KEV)Published Apr 29, 2021

CVE-2021-20090A 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…

Updated under an hour ago (2026-10-19 09:50 UTC)

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It affects buffalo wsr-2533dhpl2-bk_firmware and 1 other product. Add what you run to find out whether that includes you.

CISA lists it as known exploited since Nov 3, 2021; federal agencies had to remediate by Nov 17, 2021. Treat that date as your deadline.

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Every CVE for buffalo wsr-2533dhpl2-bk_firmware

Exploited in the last 30 days

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: 9.8 CRITICAL (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-22
Known exploited: Added to CISA KEV Nov 3, 2021; federal remediation due Nov 17, 2021Apply updates per vendor instructions.
EPSS (exploitation in the next 30 days): 99.98% (percentile 100)
Assigned by: tenable
NVD analysis: Analyzed
Record last updated: Oct 21, 2025
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

buffalo wsr-2533dhpl2-bk_firmware buffalo:wsr-2533dhpl2-bk_firmware	through 1.02	NVD
buffalo wsr-2533dhp3-bk_firmware buffalo:wsr-2533dhp3-bk_firmware	through 1.24	NVD

References

https://www.tenable.com/security/research/tra-2021-13exploit, third-party-advisory
https://www.kb.cert.org/vuls/id/914124third-party-advisory, us-government-resource
https://www.secpod.com/blog/arcadyan-based-routers-and-modems-under-active-exploitation/exploit, third-party-advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20090us-government-resource

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.