CyberSecBulletin
CVE-2022-27646NVD status: Modified

R6700v3: Stack-based Buffer Overflow

Published Updated By the CyberSecBulletin desk

CVE-2022-27646 is a high-severity stack-based buffer overflow vulnerability in R6700v3 from NETGEAR, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. Affected R6700v3 versions: 1.0.4.120_10.0.91. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.43% chance of exploitation within 30 days, higher than 73% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update R6400 Firmware to 1.0.4.126 or a later version.
  2. Update R6700 Firmware to 1.0.4.126 or a later version.
  3. Update R6900p Firmware to 1.3.3.148 or a later version.
  4. Read the advisory on kb.netgear.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
NETGEARR6700v31.0.4.120_10.0.91Not stated
NETGEARR6400 Firmwarebefore 1.0.4.1261.0.4.126
NETGEARR6700 Firmwarebefore 1.0.4.1261.0.4.126
NETGEARR6900p Firmwarebefore 1.3.3.1481.3.3.148
NETGEARR7000 Firmwarebefore 1.0.11.1341.0.11.134
NETGEARR7000p Firmwarebefore 1.3.3.1481.3.3.148
NETGEARR7850 Firmwarebefore 1.0.5.841.0.5.84
NETGEARR7960p Firmwarebefore 1.4.3.881.4.3.88
NETGEARR8000 Firmwarebefore 1.0.4.841.0.4.84
NETGEARR8000p Firmwarebefore 1.4.3.881.4.3.88
NETGEARRax200 Firmwarebefore 1.0.6.1381.0.6.138
NETGEARRax75 Firmwarebefore 1.0.6.1381.0.6.138
NETGEARRax80 Firmwarebefore 1.0.6.1381.0.6.138
NETGEARRs400 Firmwarebefore 1.5.1.861.5.1.86
NETGEARCbr40 Firmwarebefore 2.5.0.282.5.0.28
NETGEARLbr1020 Firmwarebefore 2.7.4.22.7.4.2
NETGEARLbr20 Firmwarebefore 2.7.4.22.7.4.2
NETGEARRbr10 Firmwarebefore 2.7.4.242.7.4.24
NETGEARRbr20 Firmwarebefore 2.7.4.242.7.4.24
NETGEARRbr40 Firmwarebefore 2.7.4.242.7.4.24
NETGEARRbr50 Firmwarebefore 2.7.4.242.7.4.24
NETGEARRbs10 Firmwarebefore 2.7.4.242.7.4.24
NETGEARRbs20 Firmwarebefore 2.7.4.242.7.4.24
NETGEARRbs40 Firmwarebefore 2.7.4.242.7.4.24
NETGEARRbs50 Firmwarebefore 2.7.4.242.7.4.24

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
AdjacentThe attacker must be on the same local network segment.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.8HighNVD
CVSS 3.08.0HighCNA (trendmicro.com)

Official description

This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of NETGEAR R6700v3 1.0.4.120_10.0.91 routers. Although authentication is required to exploit this vulnerability, the existing authentication mechanism can be bypassed. The specific flaw exists within the circled daemon. A crafted circleinfo.txt file can trigger an overflow of a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-15879.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Stack-based Buffer Overflow

The product writes past the end of a buffer that was allocated on the stack.

How developers prevent this class of flaw

  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
  • Use an abstraction library to abstract away risky APIs. Not a complete solution.
  • Implement and perform bounds checking on input.

More Stack-based Buffer Overflow vulnerabilities (CWE-121)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in R6700v3

All R6700v3 vulnerabilities

Recent Stack-based Buffer Overflow vulnerabilities

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