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CVE-2021-34991

29
FAUCET Score

CVE-2021-34991 is a critical vulnerability affecting NETGEAR R6400v2 1.0.4.106_10.0.80 routers, allowing network-adjacent attackers to execute arbitrary code without authentication. The flaw resides in the UPnP service's handling of the uuid request header, leading to a stack-based buffer overflow. With a CVSS score of 8.8 (HIGH), this vulnerability is easily exploitable over the network with low attack complexity, granting attackers root-level code execution and full control over the device. While not listed in CISA's KEV catalog, there is some community discussion and media coverage, indicating awareness, but no public exploit code (Metasploit, Nuclei, ExploitDB) is currently available.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.0.0.94CPE matchmatch criteria
cpe:2.3:o:netgear:ex3700_firmware:*:*:*:*:*:*:*:*
< 1.0.0.94CPE matchmatch criteria
cpe:2.3:o:netgear:ex3800_firmware:*:*:*:*:*:*:*:*
< 1.0.0.66CPE matchmatch criteria
cpe:2.3:o:netgear:ex6120_firmware:*:*:*:*:*:*:*:*
< 1.0.0.66CPE matchmatch criteria
cpe:2.3:o:netgear:ex6130_firmware:*:*:*:*:*:*:*:*
< 1.0.1.76CPE matchmatch criteria
cpe:2.3:o:netgear:r6400_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

8.8HIGH

CVSS:3.0/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
3.0

Exploit Intelligence

EPSS Score
5.67%
Probability of exploitation in next 30 days
EPSS Percentile
92.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0567 is in the 95th 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

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

Remediation

Remediation records are not available for this CVE.

References

kb.netgear.com / 000064361/Security-Advisory-for-Pre-Authentication-Buffer-Overflow-on-Multiple-Products-PSV-2021-0168
Vendor Advisory
zerodayinitiative.com / advisories/ZDI-21-1303
Third Party AdvisoryVDB Entry