CVE-2025-5399

WebSocket endless loop

Published: Jun 7, 2025Updated: Jul 30, 2025 Sources: CVE List NVD BDUCWE-835

7.5HIGH

Description

Due to a mistake in libcurl's WebSocket code, a malicious server can send a particularly crafted packet which makes libcurl get trapped in an endless busy-loop. There is no other way for the application to escape or exit this loop other than killing the thread/process. This might be used to DoS libcurl-using application.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:NConfidentiality

None

I:NIntegrity

None

A:HAvailability

High

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Weaknesses

CWE-835

Affected Products

curl

oss-project·USaka libcurl, wcurl

curlLibraryLibrary

OSS Libraries / generic-library

haxx

oss-project·SEaka haxx.se

curl

OSS Libraries

Daniel Stenberg

individual-devaka daniel stenberg (curl author), daniel.haxx.se

LibcurlLibraryLibrary

OSS Libraries / generic-library

Exploitability

1 exploit source identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

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Official Patch Available

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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique

Impact

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References

https://curl.se/docs/CVE-2025-5399.json

curl.se

https://curl.se/docs/CVE-2025-5399.html

curl.se

https://hackerone.com/reports/3168039

hackerone.com

and 3 more references View all →

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