CVE-2020-11050Network attack vector

WSS server impersonation via missing hostname verification

Published May 7, 2020 · Updated Aug 4, 2024

Improper certificate validation in Java-WebSocket 1.4.1 and earlier allows man-in-the-middle attackers to impersonate WSS servers. WebSocketClient accepts any chain-trusted TLS certificate without checking that its identity matches the requested host. An attacker positioned between a Java client and its WebSocket server can intercept or alter the protected session by presenting a valid certificate for another host.

CVSS severity9.0
Critical
EPSS probability0.77%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in Java-WebSocket 1.4.1 and earlier allows man-in-the-middle attackers to impersonate WSS servers. WebSocketClient accepts any chain-trusted TLS certificate without checking that its identity matches the requested host. An attacker positioned between a Java client and its WebSocket server can intercept or alter the protected session by presenting a valid certificate for another host.

The record

CVE
CVE-2020-11050
Published
May 7, 2020
Updated
Aug 4, 2024
Vendor
TooTallNate
Product
Java-WebSocket
Classifications
CWE-295, CWE-297, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 7, 2020CVE 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

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Is a vulnerable build present?

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

  1. Affected versionversion=<= 1.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

TooTallNate · Java-WebSocketversion=<= 1.4.1

Published CVSS scores

6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
9.0GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
8.1NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation
CWE-297Improper Validation of Certificate with Host Mismatch
T1557Adversary-in-the-Middle

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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