CVE-2021-27856

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2021-12-16. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Elevated
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 6%CVSS: 9.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
65(Track*)
EG Risk 65/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation40% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS
92.1%
KEV
Not listed

Published

December 15, 2021

Last Modified

November 21, 2024

Advisory Details (3)

Auto-updated Jul 6, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic🔴 Active Exploitation

Zero Science Lab — Information Security Research & Development Laboratory

https://www.zeroscience.mk/en/vulnerabilities/ZSL-2021-5684.php
generic
https://www.zeroscience.mk/codes/fatpipe_backdoor.txt
generic

Support

https://www.fatpipeinc.com/support/cve-list.php

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 14× in last 7d / 45× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-24 14:15 UTCEPSS rescore
  2. 2026-07-23 14:16 UTCEPSS rescore
  3. 2026-07-23 01:59 UTCEG score recompute
  4. 2026-07-22 22:46 UTCEG score recompute
  5. 2026-07-22 14:06 UTCEPSS rescore
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  7. 2026-07-21 15:22 UTCEPSS rescore
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  9. 2026-07-20 17:05 UTCEPSS rescore
  10. 2026-07-19 14:28 UTCEPSS rescore
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  15. 2026-07-16 17:00 UTCEPSS rescore
  16. 2026-07-15 16:55 UTCEPSS rescore
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  18. 2026-07-15 01:58 UTCEPSS rescore
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  21. 2026-07-13 06:10 UTCEPSS rescore
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  24. 2026-07-11 08:25 UTCEPSS rescore
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  1. 2026-07-09 19:07 UTCEPSS rescore
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  3. 2026-07-07 13:43 UTCEPSS rescore
  4. 2026-07-06 16:25 UTCEPSS rescore
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  6. 2026-07-06 02:21 UTCEPSS rescore
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  8. 2026-07-05 02:28 UTCEPSS rescore
  9. 2026-07-04 06:29 UTCEPSS rescore
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  11. 2026-07-02 16:57 UTCEPSS rescore
  12. 2026-07-01 15:03 UTCEPSS rescore
  13. 2026-06-30 23:20 UTCEPSS rescore
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  15. 2026-06-28 04:54 UTCEPSS rescore
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  17. 2026-06-27 03:06 UTCEPSS rescore
  18. 2026-06-27 03:06 UTCEPSS rescore
  19. 2026-06-25 13:48 UTCEPSS rescore
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  21. 2026-06-24 14:03 UTCEPSS rescore
  22. 2026-06-24 14:03 UTCEPSS rescore
  23. 2026-06-23 21:31 UTCEPSS rescore
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  25. 2026-06-22 14:24 UTCEPSS rescore
  26. 2026-06-22 14:24 UTCEPSS rescore
  27. 2026-06-21 14:55 UTCEPSS rescore
  28. 2026-06-21 14:54 UTCEPSS rescore
  29. 2026-06-21 01:58 UTCEPSS rescore
  30. 2026-06-21 01:58 UTCEPSS rescore
  31. 2026-06-19 19:24 UTCEPSS rescore
  32. 2026-06-19 19:24 UTCEPSS rescore
  33. 2026-06-18 17:51 UTCEPSS rescore
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  35. 2026-06-17 17:51 UTCEPSS rescore
  36. 2026-06-16 17:51 UTCEPSS rescore
  37. 2026-06-15 17:46 UTCEPSS rescore
  38. 2026-06-14 23:15 UTCEPSS rescore
  39. 2026-06-13 22:58 UTCEPSS rescore
  40. 2026-06-13 22:58 UTCEPSS rescore
  41. 2026-06-12 23:10 UTCEPSS rescore
  42. 2026-06-11 13:58 UTCEPSS rescore
  43. 2026-06-10 22:16 UTCEPSS rescore
  44. 2026-06-08 14:15 UTCEPSS rescore
  45. 2026-06-05 22:45 UTCEPSS rescore
  46. 2026-06-05 22:45 UTCEPSS rescore
  47. 2026-06-05 06:09 UTCEPSS rescore
  48. 2026-06-05 06:09 UTCEPSS rescore
  49. 2026-06-04 13:10 UTCEPSS rescore
  50. 2026-06-04 13:10 UTCEPSS rescore
  51. 2026-06-01 13:50 UTCEPSS rescore
  52. 2026-06-01 13:50 UTCEPSS rescore
  53. 2026-05-31 00:15 UTCEPSS rescore
  54. 2026-05-29 13:42 UTCEPSS rescore
  55. 2026-05-28 13:43 UTCEPSS rescore
  56. 2026-05-28 13:43 UTCEPSS rescore
  57. 2026-05-27 13:39 UTCEPSS rescore
  58. 2026-05-27 13:39 UTCEPSS rescore
  59. 2026-05-26 13:42 UTCEPSS rescore
  60. 2026-05-26 06:12 UTCEG score recompute
  61. 2026-05-26 06:12 UTCGHSA enrichment

Publicly available exploits

(1 reference)

Working exploit code is in the public domain. Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Nucleihttp/cves/2021/CVE-2021-27856.yaml
    First seen Jan 1, 2021

    FatPipe WARP/IPVPN/MPVPN - Backdoor Account

    Open source ↗

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-27856?
CVE-2021-27856 is a critical vulnerability published on December 15, 2021. 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.
When was CVE-2021-27856 disclosed?
CVE-2021-27856 was first published in the National Vulnerability Database on December 15, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-27856 actively exploited?
CVE-2021-27856 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 92.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-27856?
CVE-2021-27856 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2021-27856?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-27856, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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