CVE-2019-9099 [Critical] | Denial of Service in Mb3170 Firmware

An issue was discovered on Moxa MGate MB3170 and MB3270 devices before 4.1, MB3280 and MB3480 devices before 3.1, MB3660 devices before 2.3, and MB3180 devices before 2.1. A Buffer overflow in the built-in web server allows remote attackers to initiate DoS, and probably to execute arbitrary code (issue 1 of 2).

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	9.09%	3.94%	-5.15%
2	2026-01-12	7.02%	9.09%	+2.07%
3	2025-11-21	—	7.02%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

9.09%

3.94%

-5.15%

2026-01-12

7.02%

9.09%

+2.07%

2025-11-21

—

7.02%

—

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]
7.5	3.0	HIGH	`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	3.6	[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]

7.5

3.0

HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

3.6

[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-2019-9099

Vendor	Product	Version	Raw CPE
moxa	mb3170_firmware	<= 4.0	cpe:2.3:o:moxa:mb3170_firmware::::::::
moxa	mb3270_firmware	<= 4.0	cpe:2.3:o:moxa:mb3270_firmware::::::::
moxa	mb3180_firmware	<= 2.0	cpe:2.3:o:moxa:mb3180_firmware::::::::
moxa	mb3280_firmware	<= 3.0	cpe:2.3:o:moxa:mb3280_firmware::::::::
moxa	mb3480_firmware	<= 3.0	cpe:2.3:o:moxa:mb3480_firmware::::::::
moxa	mb3660_firmware	<= 2.2	cpe:2.3:o:moxa:mb3660_firmware::::::::

References for CVE-2019-9099

URL	Tags
https://www.moxa.com/en/support/support/security-advisory/mb3710-3180-3270-3280-3480-3660-vulnerabilities	Vendor Advisory
https://www.us-cert.gov/ics/advisories/icsa-20-056-01	Third Party Advisory US Government Resource

URL

CVE-2019-9099

Exploit prediction scoring system (EPSS) score for CVE-2019-9099

Common vulnerability scoring system (CVSS) metrics for CVE-2019-9099

Weakness enumeration for CVE-2019-9099

Affected software / configurations for CVE-2019-9099

References for CVE-2019-9099