CVE-2021-27856

CVE-2021-27856 is a critical-severity vulnerability in Fatpipeinc Ipvpn Firmware with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

• Severity: Critical (CVSS 3.x base score 9.8)
• CVSS v2: 7.5
• EPSS exploit prediction: 6% (92nd percentile)
• Actively exploited: Not listed in CISA KEV
• Affected product: Fatpipeinc Ipvpn Firmware
• Published: 2021-12-15
• Last modified: 2026-06-17

Description

FatPipe WARP, IPVPN, and MPVPN software prior to versions 10.1.2r60p91 and 10.2.2r42 includes an account named "cmuser" that has administrative privileges and no password. Older versions of FatPipe software may also be vulnerable. The FatPipe advisory identifier for this vulnerability is FPSA002.

Frequently asked questions

What is CVE-2021-27856?

FatPipe WARP, IPVPN, and MPVPN software prior to versions 10.1.2r60p91 and 10.2.2r42 includes an account named "cmuser" that has administrative privileges and no password. Older versions of FatPipe software may also be vulnerable. The FatPipe advisory identifier for this vulnerability is FPSA002.

How severe is CVE-2021-27856?

CVE-2021-27856 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-27856 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27856?

CVE-2021-27856 primarily affects Fatpipeinc Ipvpn Firmware. In total, 108 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-27856?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-27856 published?

CVE-2021-27856 was published on 2021-12-15 and last updated on 2026-06-17.

References

• https://www.fatpipeinc.com/support/cve-list.php
• https://www.zeroscience.mk/codes/fatpipe_backdoor.txt
• https://www.zeroscience.mk/en/vulnerabilities/ZSL-2021-5684.php

Affected products (108)

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

More vulnerabilities in Fatpipeinc Ipvpn Firmware

• CVE-2021-27860 — Critical (CVSS 9.8): A vulnerability in the web management interface of FatPipe WARP, IPVPN, and MPVPN software prior to versions…
• CVE-2021-27859 — High (CVSS 8.8): A missing authorization vulnerability in the web management interface of FatPipe WARP, IPVPN, and MPVPN software prior…
• CVE-2021-27855 — High (CVSS 8.8): FatPipe WARP, IPVPN, and MPVPN software prior to versions 10.1.2r60p91 and 10.2.2r42 allows a remote, authenticated…
• CVE-2021-27857 — High (CVSS 7.5): A missing authorization vulnerability in the web management interface of FatPipe WARP, IPVPN, and MPVPN software prior…
• CVE-2021-27858 — Medium (CVSS 5.3): A missing authorization vulnerability in the web management interface of FatPipe WARP, IPVPN, and MPVPN software prior…

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