Patchfirst
CVE-2021-20090 KEVPublic exploit Critical · 9.8 EPSS >99.9%

Arcadyan Buffalo Firmware Path Traversal Vulnerability

Arcadyan · Buffalo Firmware

Summary

The Buffalo firmware from Arcadyan contains a path traversal flaw in the web interfaces of the WSR-2533DHPL2 and WSR-2533DHP3 routers, where improper limitation of a pathname to a restricted directory exists. An unauthenticated remote attacker with network access can exploit this to bypass authentication, requiring no privileges, no user interaction, and no particular non-default configuration.

Official description · NVD

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.

Breakdown
73.7 / 100
Exploited
Yes, in CISA KEV
Reports
1
Tactics
4/15

How an attack unfolds

Based on mappings. Select a step to see the evidence.
  1. How attackers get in

  2. What they do

First seen exploited 3 months after disclosure.

  1. Disclosedday 0
  2. First seen exploitedVulnCheck KEV evidence+3 mo
  3. Added to CISA KEVEU database agrees+6 mo
  4. Named in a threat reportaquasec.com+4 yrs

CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.

techniques

2 , grouped by in kill-chain order, 3 cited passages 2

Initial AccessTA0001

Valid Accounts T1078 Medium also Persistence, Privilege Escalation, Stealth
AI mapping from the description · primary impact

Authentication bypass yields valid-access equivalent

could allow unauthenticated remote attackers to bypass authentication
From the official description (NVD) Original (opens in a new tab) ↗
Exploit Public-Facing Application T1190 Medium
AI mapping from the description · how it is exploited

Exploits exposed web interface via path traversal; keyword query KW:T1190:1

path traversal vulnerability in the web interfaces
From the official description (NVD) Original (opens in a new tab) ↗
Exploit Public-Facing Application: Exploits vulnerabilities in IoT devices, routers, and servers such as HugeGraph (CVE-2024-27348) and Arcadyan firmware (CVE-2021-20090).
Matrix Unleashes A New Widespread DDoS Campaign aquasec.com, 26 Nov 2024 Original (opens in a new tab) ↗

Detection

1 rule for this CVE · 205 general rules for its techniques

Rules for this CVE

1 that reference CVE-2021-20090 directly.

Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.

What security researchers reported

Named in 1 threat report
1 reportAqua SecurityNov 2024

Reports are matched by finding the exact id CVE-2021-20090 in their text; nobody has reviewed the match. One passage is shown per report, at most 320 characters, linked to the original.

Also mentioned in 50 community threat pulses (AlienVault OTX)

Weaker evidence

Pulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.

References

4 links, grouped by NVD tag (3 duplicates merged)
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