CVE-2021-31606Public exploitNetwork attack vector

Unauthenticated client disconnection via unchecked POST route

Published Sep 27, 2021 · Updated Aug 3, 2024

Authorization bypass in openvpn-monitor 1.1.3 and earlier allows remote attackers to disconnect arbitrary VPN clients via HTTP POST requests. The root POST route accepts vpn_id, ip, port, and client_id fields and invokes rendering without checking the site's show_disconnect setting, which results in a kill command being sent to the OpenVPN management socket. No authentication or user interaction is required, and the bypass works even when the disconnect button is hidden, interrupting selected client sessions rather than stopping the server.

CVSS severity7.5
High
EPSS probability2.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in openvpn-monitor 1.1.3 and earlier allows remote attackers to disconnect arbitrary VPN clients via HTTP POST requests. The root POST route accepts vpn_id, ip, port, and client_id fields and invokes rendering without checking the site's show_disconnect setting, which results in a kill command being sent to the OpenVPN management socket. No authentication or user interaction is required, and the bypass works even when the disconnect button is hidden, interrupting selected client sessions rather than stopping the server.

The record

CVE
CVE-2021-31606
Published
Sep 27, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-287, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 27, 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

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
5.8Compass SecurityCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/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 exploitPublished

Weakness, pattern, technique

CWE-287Improper Authentication
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

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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