CVE-2021-20677Network attack vector

Authenticated service reboot via crafted maintenance command

Published Mar 26, 2021 · Updated Aug 3, 2024

Command-handling denial of service in NEC UNIVERGE Aspire PBX releases allows remote authenticated users to reboot systems. The remote system maintenance feature mishandles a specially crafted command, takes the PBX down, and triggers a reboot. Exploitation requires authenticated maintenance access to a feature disabled by default; the bounded consequence is temporary telephony service interruption.

CVSS severity3.1
Low
EPSS probability0.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command-handling denial of service in NEC UNIVERGE Aspire PBX releases allows remote authenticated users to reboot systems. The remote system maintenance feature mishandles a specially crafted command, takes the PBX down, and triggers a reboot. Exploitation requires authenticated maintenance access to a feature disabled by default; the bounded consequence is temporary telephony service interruption.

The record

CVE
CVE-2021-20677
Published
Mar 26, 2021
Updated
Aug 3, 2024
Vendor
NEC Platforms, Ltd.
Product
UNIVERGE Aspire
Classifications
T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 26, 2021CVE 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=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

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

NEC Platforms, Ltd. · UNIVERGE Aspireversion=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

Published CVSS scores

3.1NIST NVDCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
3.1JPCERT/CCCVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:N/A:P
3.5JPCERT/CCAV:N/AC:M/Au:S/C:N/I:N/A:P

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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