CVE-2021-27795Network attack vector

License forgery via weak license-string cryptography

Published Dec 6, 2023 · Updated Aug 3, 2024

Cryptographic weakness in Brocade Fabric OS versions using license strings allows attackers to activate forged keys on affected switches. The license-processing logic authenticates counterfeit license strings, then interprets unauthorized flags or fields absent from valid keys. Exploitation requires switch-specific identifiers and installation of the crafted key; resulting behavior can expose profile data, corrupt user data, enable unsupported features, or install unauthorized FOS releases.

CVSS severity6.4
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cryptographic weakness in Brocade Fabric OS versions using license strings allows attackers to activate forged keys on affected switches. The license-processing logic authenticates counterfeit license strings, then interprets unauthorized flags or fields absent from valid keys. Exploitation requires switch-specific identifiers and installation of the crafted key; resulting behavior can expose profile data, corrupt user data, enable unsupported features, or install unauthorized FOS releases.

The record

CVE
CVE-2021-27795
Published
Dec 6, 2023
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-327
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 6, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.4Brocade Communications Systems, LLCCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:H
8.1NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-327Use of a Broken or Risky Cryptographic Algorithm

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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