CVE-2021-3849

An authentication bypass vulnerability was discovered in the web interface of the Lenovo Fan Power Controller2 (FPC2) and Lenovo System Management Module (SMM) firmware that could allow an unauthenticated attacker to execute commands on the SMM and FPC2. SMM2 is not affected.

Published: 2022-04-22 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-3849 is rated Moderate Risk (62/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 1.19%). 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-2021-3849

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 0.70% 1.19% +0.49%
2 2026-05-03 0.51% 0.70% +0.19%
3 2025-05-04 — 0.51% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3849

CVSS metrics for this CVE.

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]

Weakness enumeration for CVE-2021-3849

Affected software / configurations for CVE-2021-3849

Vendor Product Version Raw CPE
lenovo nextscale_n1200_enclosure_firmware < fhet50b-2.90 cpe:2.3:o:lenovo:nextscale_n1200_enclosure_firmware:*:*:*:*:*:*:*:*
lenovo thinkagile_hx_enclosure_certified_node_firmware < tesm28b-1.21 cpe:2.3:o:lenovo:thinkagile_hx_enclosure_certified_node_firmware:*:*:*:*:*:*:*:*
lenovo thinkagile_vx_enclosure_firmware < tesm28b-1.21 cpe:2.3:o:lenovo:thinkagile_vx_enclosure_firmware:*:*:*:*:*:*:*:*
lenovo thinksystem_d2_enclosure_firmware < tesm28b-1.21 cpe:2.3:o:lenovo:thinksystem_d2_enclosure_firmware:*:*:*:*:*:*:*:*
ibm nextscale_fan_power_controller_firmware < 44a-3.70 cpe:2.3:o:ibm:nextscale_fan_power_controller_firmware:*:*:*:*:*:*:*:*

References for CVE-2021-3849

cvelogic Threat Intelligence