CVE-2025-43855Public exploitNetwork attack vector

Server crash via rethrown connectionParams parse error

Published Apr 24, 2025 · Updated May 14, 2025

Denial of service in tRPC 11.0.0 through 11.1.0 allows remote attackers to crash WebSocket server processes with invalid connectionParams. The WebSocket createCtxPromise error handler catches a parseConnectionParamsFromUnknown rejection, responds, then rethrows it from the message event without a higher-level handler. The server must expose WebSockets with createContext configured; one crafted unauthenticated connectionParams message terminates the entire process.

CVSS severity8.7
High
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in tRPC 11.0.0 through 11.1.0 allows remote attackers to crash WebSocket server processes with invalid connectionParams. The WebSocket createCtxPromise error handler catches a parseConnectionParamsFromUnknown rejection, responds, then rethrows it from the message event without a higher-level handler. The server must expose WebSockets with createContext configured; one crafted unauthenticated connectionParams message terminates the entire process.

The record

CVE
CVE-2025-43855
Published
Apr 24, 2025
Updated
May 14, 2025
Vendor
tRPC
Product
tRPC
Classifications
CWE-248, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 24, 2025CVE publishedPublication date reported by the CVE source.
  2. May 14, 2025Record 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=>= 11.0.0, < 11.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

tRPC · tRPCversion=>= 11.0.0, < 11.1.1

Published CVSS scores

8.7GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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-248Uncaught Exception
T1499.004Application 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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