CVE-2021-20677

UNIVERGE Aspire series PBX (UNIVERGE Aspire WX from 1.00 to 3.51, UNIVERGE Aspire UX from 1.00 to 9.70, UNIVERGE SV9100 from 1.00 to 10.70, and SL2100 from 1.00 to 3.00) allows a remote authenticated attacker to cause system down and a denial of service (DoS) condition by sending a specially crafted command.

Published: 2021-03-26 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-20677 is rated Low Risk (30.9/100): CVSS Low severity, with medium exploitation likelihood (EPSS 0.30%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

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-2021-20677

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 2025-11-21 0.42% 0.30% -0.12%
2 2025-11-18 0.30% 0.42% +0.12%
3 2025-03-30 — 0.30% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-20677

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
3.1 3.1 LOW
CVSS:3.1/AV:N/AC:H/PR:L/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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
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.
 1.6 1.4 [email protected]
3.5 2.0 LOW
AV:N/AC:M/Au:S/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 6.8 2.9 [email protected]

Weakness enumeration for CVE-2021-20677

Affected software / configurations for CVE-2021-20677

Vendor Product Version Raw CPE
necplatforms univerge_aspire_wx_firmware >= 1.00, <= 3.51 cpe:2.3:o:necplatforms:univerge_aspire_wx_firmware:*:*:*:*:*:*:*:*
necplatforms univerge_aspire_ux_firmware >= 1.00, <= 9.70 cpe:2.3:o:necplatforms:univerge_aspire_ux_firmware:*:*:*:*:*:*:*:*
necplatforms univerge_sv9100_firmware >= 1.00, <= 10.70 cpe:2.3:o:necplatforms:univerge_sv9100_firmware:*:*:*:*:*:*:*:*
necplatforms sl2100_firmware >= 1.00, <= 3.00 cpe:2.3:o:necplatforms:sl2100_firmware:*:*:*:*:*:*:*:*

References for CVE-2021-20677

cvelogic Threat Intelligence