CVE-2018-21134 [Critical] | Out-of-bounds Write in R6700 Firmware

Certain NETGEAR devices are affected by a stack-based buffer overflow by an unauthenticated attacker. This affects R6700 before 1.0.1.48, R7900 before 1.0.2.16, R6900 before 1.0.1.48, R7000P before 1.3.1.44, R6900P before 1.3.1.44, R6250 before 1.0.4.30, R6300v2 before 1.0.4.32, R6400 before 1.0.1.44, R6400v2 before 1.0.2.60, R7000 before 1.0.9.34, R7100LG before 1.0.0.48, R7300 before 1.0.0.68, R8000 before 1.0.4.18, R8000P before 1.4.1.24, R7900P before 1.4.1.24, R8500 before 1.0.2.122, R8300 before 1.0.2.122, WN2500RPv2 before 1.0.1.54, EX3700 before 1.0.0.72, EX3800 before 1.0.0.72, EX6000 before 1.0.0.32, EX6100 before 1.0.2.24, EX6120 before 1.0.0.42, EX6130 before 1.0.0.24, EX6150v1 before 1.0.0.42, EX6200 before 1.0.3.88, EX7000 before 1.0.0.66, D7000v2 before 1.0.0.51, D6220 before 1.0.0.46, D6400 before 1.0.0.82, and D8500 before 1.0.3.42.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.53%	1.26%	+0.74%
2	2025-03-30	0.76%	0.53%	-0.23%
3	2025-03-29	—	0.76%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.53%

1.26%

+0.74%

2025-03-30

0.76%

0.53%

-0.23%

2025-03-29

—

0.76%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
9.8	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	5.9	[email protected]
6.8	3.0	MEDIUM	`CVSS:3.0/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L` Click to expand Attack vector (AV:A) Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	2.1	4.7	[email protected]
7.5	2.0	HIGH	`AV:N/AC:L/Au:N/C:P/I:P/A:P` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	10.0	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

9.8

3.1

CRITICAL

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

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

5.9

[email protected]

6.8

3.0

MEDIUM

CVSS:3.0/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L Click to expand

Attack vector (AV:A): Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

2.1

4.7

[email protected]

7.5

2.0

HIGH

AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

10.0

6.4

[email protected]

Affected software / configurations for CVE-2018-21134

Vendor	Product	Version	Raw CPE
netgear	r6700_firmware	< 1.0.1.48	cpe:2.3:o:netgear:r6700_firmware::::::::
netgear	r7900_firmware	< 1.0.2.16	cpe:2.3:o:netgear:r7900_firmware::::::::
netgear	r6900_firmware	< 1.0.1.48	cpe:2.3:o:netgear:r6900_firmware::::::::
netgear	r7000p_firmware	< 1.3.1.44	cpe:2.3:o:netgear:r7000p_firmware::::::::
netgear	r6900p_firmware	< 1.3.1.44	cpe:2.3:o:netgear:r6900p_firmware::::::::
netgear	r6250_firmware	< 1.0.4.30	cpe:2.3:o:netgear:r6250_firmware::::::::
netgear	r6300_firmware	< 1.0.4.32	cpe:2.3:o:netgear:r6300_firmware::::::::
netgear	r6400_firmware	< 1.0.1.44	cpe:2.3:o:netgear:r6400_firmware::::::::
netgear	r6400_firmware	< 1.0.2.60	cpe:2.3:o:netgear:r6400_firmware::::::::
netgear	r7000_firmware	< 1.0.9.34	cpe:2.3:o:netgear:r7000_firmware::::::::
netgear	r7100lg_firmware	< 1.0.0.48	cpe:2.3:o:netgear:r7100lg_firmware::::::::
netgear	r7300_firmware	< 1.0.0.68	cpe:2.3:o:netgear:r7300_firmware::::::::
netgear	r8000_firmware	< 1.0.4.18	cpe:2.3:o:netgear:r8000_firmware::::::::
netgear	r8000p_firmware	< 1.4.1.24	cpe:2.3:o:netgear:r8000p_firmware::::::::
netgear	r7900p_firmware	< 1.4.1.24	cpe:2.3:o:netgear:r7900p_firmware::::::::
netgear	r8500_firmware	< 1.0.2.122	cpe:2.3:o:netgear:r8500_firmware::::::::
netgear	r8300_firmware	< 1.0.2.122	cpe:2.3:o:netgear:r8300_firmware::::::::
netgear	wn2500rp_firmware	< 1.0.1.54	cpe:2.3:o:netgear:wn2500rp_firmware::::::::
netgear	ex3700_firmware	< 1.0.0.72	cpe:2.3:o:netgear:ex3700_firmware::::::::
netgear	ex3800_firmware	< 1.0.0.72	cpe:2.3:o:netgear:ex3800_firmware::::::::
netgear	ex6000_firmware	< 1.0.0.32	cpe:2.3:o:netgear:ex6000_firmware::::::::
netgear	ex6100_firmware	< 1.0.2.24	cpe:2.3:o:netgear:ex6100_firmware::::::::
netgear	ex6120_firmware	< 1.0.0.42	cpe:2.3:o:netgear:ex6120_firmware::::::::
netgear	ex6130_firmware	< 1.0.0.24	cpe:2.3:o:netgear:ex6130_firmware::::::::
netgear	ex6150_firmware	< 1.0.0.42	cpe:2.3:o:netgear:ex6150_firmware::::::::
netgear	ex6200_firmware	< 1.0.3.88	cpe:2.3:o:netgear:ex6200_firmware::::::::
netgear	ex7000_firmware	< 1.0.0.66	cpe:2.3:o:netgear:ex7000_firmware::::::::
netgear	d7000_firmware	< 1.0.0.51	cpe:2.3:o:netgear:d7000_firmware::::::::
netgear	d6220_firmware	< 1.0.0.46	cpe:2.3:o:netgear:d6220_firmware::::::::
netgear	d6400_firmware	< 1.0.0.82	cpe:2.3:o:netgear:d6400_firmware::::::::
netgear	d8500_firmware	< 1.0.3.42	cpe:2.3:o:netgear:d8500_firmware::::::::

References for CVE-2018-21134

URL	Tags
https://kb.netgear.com/000060226/Security-Advisory-for-Pre-Authentication-Stack-Overflow-on-Some-Routers-and-Wireless-Extenders-PSV-2017-2019	Vendor Advisory

URL

CVE-2018-21134

Exploit prediction scoring system (EPSS) score for CVE-2018-21134

Common vulnerability scoring system (CVSS) metrics for CVE-2018-21134

Weakness enumeration for CVE-2018-21134

Affected software / configurations for CVE-2018-21134

References for CVE-2018-21134