CVE-2025-5399

WebSocket endless loop

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.

7.5

CVSS

Severity: High

CVSS 3.1 •

EPSS 0.02%

Affected: curl curl

References

Link	Tags
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

Frequently Asked Questions

What is the severity of CVE-2025-5399?: CVE-2025-5399 has been scored as a high severity vulnerability.
How to fix CVE-2025-5399?: To fix CVE-2025-5399, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2025-5399 being actively exploited in the wild?: As for now, there are no information to confirm that CVE-2025-5399 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-5399?: CVE-2025-5399 affects curl curl.

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