CVE-2021-27793

ntermittent authorization failure in aaa tacacs+ with Brocade Fabric OS versions before Brocade Fabric OS v9.0.1b and after 9.0.0, also in Brocade Fabric OS before Brocade Fabric OS v8.2.3a and after v8.2.0 could cause a user with a valid account to be unable to log into the switch.

Published: 2021-08-12 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-27793 is rated Moderate Risk (41/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.91%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-27793

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.32% 0.91% +0.58%
2 2025-03-30 0.39% 0.32% -0.06%
3 2025-03-29 — 0.39% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-27793

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L 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:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/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:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-27793

Affected software / configurations for CVE-2021-27793

Vendor Product Version Raw CPE
broadcom fabric_operating_system >= 8.2.0, < 8.2.3 cpe:2.3:o:broadcom:fabric_operating_system:*:*:*:*:*:*:*:*
broadcom fabric_operating_system >= 9.0.0, < 9.0.1 cpe:2.3:o:broadcom:fabric_operating_system:*:*:*:*:*:*:*:*
broadcom fabric_operating_system 8.2.3 cpe:2.3:o:broadcom:fabric_operating_system:8.2.3:*:*:*:*:*:*:*
broadcom fabric_operating_system 9.0.1 cpe:2.3:o:broadcom:fabric_operating_system:9.0.1:*:*:*:*:*:*:*
broadcom fabric_operating_system 9.0.1a cpe:2.3:o:broadcom:fabric_operating_system:9.0.1a:*:*:*:*:*:*:*

References for CVE-2021-27793

cvelogic Threat Intelligence