CVE-2018-21198 [Medium] | Out-of-bounds Write in D6100 Firmware

Certain NETGEAR devices are affected by a stack-based buffer overflow by an authenticated user. This affects D6100 before 1.0.0.57, R7800 before 1.2.0.44, R9000 before 1.0.2.52, WNDR3700v4 before 1.0.2.92, WNDR4300 before 1.0.2.94, WNDR4300v2 before 1.0.0.54, WNDR4500v3 before 1.0.0.54, and WNR2000v5 before 1.0.0.62.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.12%	0.57%	+0.44%
2	2025-03-30	0.31%	0.12%	-0.19%
3	2025-03-29	—	0.31%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.12%

0.57%

+0.44%

2025-03-30

0.31%

0.12%

-0.19%

2025-03-29

—

0.31%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
6.8	3.1	MEDIUM	`CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H` 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:H) They need powerful rights—admin, root, or similar—before this pays off. 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.	0.9	5.9	[email protected]
6.8	3.0	MEDIUM	`CVSS:3.0/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H` 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:H) They need powerful rights—admin, root, or similar—before this pays off. 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.	0.9	5.9	[email protected]
5.2	2.0	MEDIUM	`AV:A/AC:L/Au:S/C:P/I:P/A:P` Click to expand Access vector (AV:A) Requires access to an adjacent network segment. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:S) A single authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	5.1	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

6.8

3.1

MEDIUM

CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H 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:H): They need powerful rights—admin, root, or similar—before this pays off.
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.

0.9

5.9

[email protected]

6.8

3.0

MEDIUM

CVSS:3.0/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H 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:H): They need powerful rights—admin, root, or similar—before this pays off.
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.

0.9

5.9

[email protected]

5.2

2.0

MEDIUM

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

Access vector (AV:A): Requires access to an adjacent network segment.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:S): A single authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

5.1

6.4

[email protected]

Affected software / configurations for CVE-2018-21198

Vendor	Product	Version	Raw CPE
netgear	d6100_firmware	< 1.0.0.57	cpe:2.3:o:netgear:d6100_firmware::::::::
netgear	r7800_firmware	< 1.0.2.44	cpe:2.3:o:netgear:r7800_firmware::::::::
netgear	r9000_firmware	< 1.0.2.52	cpe:2.3:o:netgear:r9000_firmware::::::::
netgear	wndr3700_firmware	< 1.0.2.92	cpe:2.3:o:netgear:wndr3700_firmware::::::::
netgear	wndr4300_firmware	< 1.0.2.94	cpe:2.3:o:netgear:wndr4300_firmware::::::::
netgear	wndr4300_firmware	< 1.0.0.54	cpe:2.3:o:netgear:wndr4300_firmware::::::::
netgear	wndr4500_firmware	< 1.0.0.54	cpe:2.3:o:netgear:wndr4500_firmware::::::::
netgear	wnr2000_firmware	< 1.0.0.62	cpe:2.3:o:netgear:wnr2000_firmware::::::::

References for CVE-2018-21198

URL	Tags
https://kb.netgear.com/000055151/Security-Advisory-for-Post-Authentication-Stack-Overflow-on-Some-Routers-and-Gateways-PSV-2017-2594	Vendor Advisory

URL

CVE-2018-21198

Exploit prediction scoring system (EPSS) score for CVE-2018-21198

Common vulnerability scoring system (CVSS) metrics for CVE-2018-21198

Weakness enumeration for CVE-2018-21198

Affected software / configurations for CVE-2018-21198

References for CVE-2018-21198