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Exploited vulnerability · CISA KEV

Is CVE-2021-20090 exploited? Yes: in CISA KEV since 3 Nov 2021

Gociux · Arcadyan Buffalo Firmware · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2021-20090, Arcadyan Buffalo Firmware Path Traversal Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 3 Nov 2021, 188 days after it was published. It affects Arcadyan Buffalo Firmware. If you run it, CISA's required action is: Apply updates per vendor instructions.

exploitedYesCISA KEV · 3 Nov 2021
ransomwareNot knownno confirmed use
EPSStop 1%among the most likely CVEs to be exploited
severity9.8CVSS 3.1 · critical
US federal due17 Nov 2021BOD 22-01 deadline

What it is

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.

VendorArcadyan (1 exploited CVE in KEV)
ProductBuffalo Firmware
VulnerabilityArcadyan Buffalo Firmware Path Traversal Vulnerability
WeaknessCWE-22
Published29 Apr 2021
Added to KEV3 Nov 2021
Reported by (CNA)tenable

What to do

  1. Check whether you run it. Look for Buffalo Firmware in your asset inventory, including appliances and cloud images. Stack check lists every exploited Arcadyan CVE at once.
  2. Apply the fix. Apply updates per vendor instructions.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 29 Apr 2021.
  4. Get told next time. Email alerts when CISA adds a CVE for Arcadyan.

References

Questions

Is CVE-2021-20090 being exploited?

Yes. CISA added CVE-2021-20090 to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, which means there is reliable evidence of exploitation in the wild.

Is CVE-2021-20090 used in ransomware attacks?

CISA does not list known ransomware use for it. That can change, and exploitation alone is reason to fix it first.

How do I fix CVE-2021-20090?

Apply updates per vendor instructions. Check Arcadyan's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected Buffalo Firmware and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in November 2021 · act-now radar.

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