CVE-2025-5399

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.

CVSS Metrics

• v3.1•HIGH•Score: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 1.23%• Percentile: 65%

Techniques & Countermeasures

• CWE-835•Loop with Unreachable Exit Condition ('Infinite Loop')

  The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

Affected Systems

• curl•curl

  8.14.0 | 8.13.0

• haxx•curl

  ≥ 8.13.0, < 8.14.1

References (4)

• https://curl.se/docs/CVE-2025-5399.json
• https://curl.se/docs/CVE-2025-5399.html
• https://hackerone.com/reports/3168039
• http://www.openwall.com/lists/oss-security/2025/06/04/2