CVE-2020-5686Network attack vector

Information disclosure via TSMM authentication bypass

Published Jan 13, 2021 · Updated Aug 4, 2024

Improper authentication in NEC UNIVERGE SV9500 V1 through V7 and SV8500 S6 through S8 allows remote attackers to disclose information. The TSMM remote-maintenance console accepts a specially crafted request to a specific URL as an arbitrary administrator. Network access to TSMM is required; successful exploitation exposes maintenance access and information, while this CVE does not establish command execution or service interruption.

CVSS severity7.6
High
EPSS probability1.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in NEC UNIVERGE SV9500 V1 through V7 and SV8500 S6 through S8 allows remote attackers to disclose information. The TSMM remote-maintenance console accepts a specially crafted request to a specific URL as an arbitrary administrator. Network access to TSMM is required; successful exploitation exposes maintenance access and information, while this CVE does not establish command execution or service interruption.

The record

CVE
CVE-2020-5686
Published
Jan 13, 2021
Updated
Aug 4, 2024
Vendor
NEC Corporation
Product
UNIVERGE SV9500/SV8500 series
Classifications
CWE-287, CWE-303, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=SV9500 series from V1 to V7and SV8500 series from S6 to S8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

NEC Corporation · UNIVERGE SV9500/SV8500 seriesversion=SV9500 series from V1 to V7and SV8500 series from S6 to S8

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
5.8JPCERT/CC and IPAAV:A/AC:L/Au:N/C:P/I:P/A:P
7.6JPCERT/CC and IPACVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

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-287Improper Authentication
CWE-303Incorrect Implementation of Authentication Algorithm
T1190Exploit Public-Facing Application

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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