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CVE-2021-20139

29
FAUCET Score

CVE-2021-20139 is an unauthenticated command injection vulnerability affecting Gryphon Tower routers, specifically within the controller_server service. An attacker on the same network can execute arbitrary commands as root by sending a specially crafted packet to port 9999. This vulnerability carries a high CVSS score of 8.8, indicating a critical risk due to its network-adjacent attack vector, low complexity, and complete compromise of confidentiality, integrity, and availability. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
<= 04.0004.12CPE matchmatch criteria
cpe:2.3:o:gryphonconnect:gryphon_tower_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
ADJACENT_NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.98%
Probability of exploitation in next 30 days
EPSS Percentile
89.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0398 is in the 94th percentile among its peer group of 1,875 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.2 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (3)

giteavendor investigatingvia llm_extracted
opensshvendor investigatingvia llm_extracted
railsvendor investigatingvia llm_extracted

Vendor Advisories (3)

opensshllm-openssh-673dfebe8517c769CRITICAL

Multiple Vulnerabilities in Gryphon Tower Router

Dec 7, 2021
giteallm-gitea-1cc4697638d33921CRITICAL

Multiple Vulnerabilities in Gryphon Tower Router

Dec 7, 2021
railsllm-rails-a3fab0411404ce49CRITICAL

Multiple Vulnerabilities in Gryphon Tower Router

Dec 7, 2021

References

tenable.com / security/research/tra-2021-51
ExploitVendor Advisory