CVE-2025-5399

WebSocket endless loop

Published Jun 7, 2025 CVSS 3.1 · 7.5 High EPSS 1.4% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2025-17371 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.
History
Type Values Removed Values Added
First Time appeared Haxx
Haxx curl
CPEs cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*
Vendors & Products Haxx
Haxx curl
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title WebSocket endless loop
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
curl
Published
Updated
Jun 9, 2025, 1:20 PM
Reserved
May 31, 2025, 3:02 PM
Status
Analyzed
Published
Jun 7, 2025, 8:15 AM
Modified
Jun 17, 2026, 9:47 AM
Severity
Moderate
Public date
Jun 7, 2025, 7:49 AM