CVE-2021-27856 [Critical] | Security Vulnerability in Ipvpn Firmware

CVE-2021-27856 is rated High Risk (78.8/100): CVSS Critical severity, with high exploitation likelihood (EPSS 70.89%, 99th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +24.59% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-05-26	46.30%	70.89%	+24.59%
2	2026-03-24	50.02%	46.30%	-3.71%
3	2026-03-06	—	50.02%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-05-26

46.30%

70.89%

+24.59%

2026-03-24

50.02%

46.30%

-3.71%

2026-03-06

—

50.02%

—

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]
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	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]

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

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-2021-27856

Vendor	Product	Version	Raw CPE
fatpipeinc	ipvpn_firmware	5.2.0	cpe:2.3:o:fatpipeinc:ipvpn_firmware:5.2.0:r34::::::
fatpipeinc	ipvpn_firmware	6.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:6.1.2:r70p26::::::
fatpipeinc	ipvpn_firmware	6.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:6.1.2:r70p45-m::::::
fatpipeinc	ipvpn_firmware	6.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:6.1.2:r70p75-m::::::
fatpipeinc	ipvpn_firmware	7.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:7.1.2:r39::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r129::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r144::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r150::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r156::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r161p12::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r161p16::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r161p17::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r161p2::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r161p20::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r161p26::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r161p3::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r164::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r164p4::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r164p5::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r165::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r180p2::::::
fatpipeinc	ipvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:9.1.2:r185::::::
fatpipeinc	ipvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.1.2:r60p10::::::
fatpipeinc	ipvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.1.2:r60p13::::::
fatpipeinc	ipvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.1.2:r60p32::::::
fatpipeinc	ipvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.1.2:r60p35::::::
fatpipeinc	ipvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.1.2:r60p45::::::
fatpipeinc	ipvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.1.2:r60p55::::::
fatpipeinc	ipvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.1.2:r60p58::::::
fatpipeinc	ipvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.1.2:r60p58s1::::::
fatpipeinc	ipvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.1.2:r60p65::::::
fatpipeinc	ipvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.1.2:r60p71::::::
fatpipeinc	ipvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.1.2:r60p82::::::
fatpipeinc	ipvpn_firmware	10.2.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.2.2:r10::::::
fatpipeinc	ipvpn_firmware	10.2.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.2.2:r25::::::
fatpipeinc	ipvpn_firmware	10.2.2	cpe:2.3:o:fatpipeinc:ipvpn_firmware:10.2.2:r38::::::
fatpipeinc	mpvpn_firmware	5.2.0	cpe:2.3:o:fatpipeinc:mpvpn_firmware:5.2.0:r34::::::
fatpipeinc	mpvpn_firmware	6.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:6.1.2:r70p26::::::
fatpipeinc	mpvpn_firmware	6.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:6.1.2:r70p45-m::::::
fatpipeinc	mpvpn_firmware	6.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:6.1.2:r70p75-m::::::
fatpipeinc	mpvpn_firmware	7.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:7.1.2:r39::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r129::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r144::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r150::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r156::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r161p12::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r161p16::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r161p17::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r161p2::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r161p20::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r161p26::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r161p3::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r164::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r164p4::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r164p5::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r165::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r180p2::::::
fatpipeinc	mpvpn_firmware	9.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:9.1.2:r185::::::
fatpipeinc	mpvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.1.2:r60p10::::::
fatpipeinc	mpvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.1.2:r60p13::::::
fatpipeinc	mpvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.1.2:r60p32::::::
fatpipeinc	mpvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.1.2:r60p35::::::
fatpipeinc	mpvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.1.2:r60p45::::::
fatpipeinc	mpvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.1.2:r60p55::::::
fatpipeinc	mpvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.1.2:r60p58::::::
fatpipeinc	mpvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.1.2:r60p58s1::::::
fatpipeinc	mpvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.1.2:r60p65::::::
fatpipeinc	mpvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.1.2:r60p71::::::
fatpipeinc	mpvpn_firmware	10.1.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.1.2:r60p82::::::
fatpipeinc	mpvpn_firmware	10.2.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.2.2:r10::::::
fatpipeinc	mpvpn_firmware	10.2.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.2.2:r25::::::
fatpipeinc	mpvpn_firmware	10.2.2	cpe:2.3:o:fatpipeinc:mpvpn_firmware:10.2.2:r38::::::
fatpipeinc	warp_firmware	5.2.0	cpe:2.3:o:fatpipeinc:warp_firmware:5.2.0:r34::::::
fatpipeinc	warp_firmware	6.1.2	cpe:2.3:o:fatpipeinc:warp_firmware:6.1.2:r70p26::::::
fatpipeinc	warp_firmware	6.1.2	cpe:2.3:o:fatpipeinc:warp_firmware:6.1.2:r70p45-m::::::
fatpipeinc	warp_firmware	6.1.2	cpe:2.3:o:fatpipeinc:warp_firmware:6.1.2:r70p75-m::::::
fatpipeinc	warp_firmware	7.1.2	cpe:2.3:o:fatpipeinc:warp_firmware:7.1.2:r39::::::
fatpipeinc	warp_firmware	9.1.2	cpe:2.3:o:fatpipeinc:warp_firmware:9.1.2:r129::::::
fatpipeinc	warp_firmware	9.1.2	cpe:2.3:o:fatpipeinc:warp_firmware:9.1.2:r144::::::
fatpipeinc	warp_firmware	9.1.2	cpe:2.3:o:fatpipeinc:warp_firmware:9.1.2:r150::::::

References for CVE-2021-27856

URL	Tags
https://www.fatpipeinc.com/support/cve-list.php	Vendor Advisory
https://www.zeroscience.mk/codes/fatpipe_backdoor.txt	Third Party Advisory
https://www.zeroscience.mk/en/vulnerabilities/ZSL-2021-5684.php	Third Party Advisory

URL

CVE-2021-27856 | FatPipe software administrative account with no password

Exploit prediction scoring system (EPSS) score for CVE-2021-27856

Common vulnerability scoring system (CVSS) metrics for CVE-2021-27856

Weakness enumeration for CVE-2021-27856

Affected software / configurations for CVE-2021-27856

References for CVE-2021-27856