Authentication bypass via path traversal in Buffalo WSR-2533DHPL2/WSR-2533DHP3 web interface
CVE-2021-20090 is a path traversal vulnerability in the web management interface of Buffalo WSR-2533DHPL2 firmware version 1.02 and earlier and WSR-2533DHP3 firmware version 1.24 and earlier. The flaw affects Arcadyan-based router firmware and allows a remote, unauthenticated attacker to use crafted traversal sequences against the web interface to reach protected resources without authenticating. According to the provided advisory context, exploitation can expose sensitive information, including valid request tokens, and can permit modification of router configuration. In effect, the traversal condition enables authentication bypass by granting access to resources that should be restricted behind the administrative interface.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
2 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A vulnerability in Arcadyan-based router firmware, exploited for unauthorized access and botnet recruitment.
A directory traversal vulnerability in certain router models that allows unauthenticated remote attackers to access sensitive information or execute commands.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.