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 v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-835 CWE-835

Affected Products

Vendor	Product	Versions
haxx	curl	8.13.0 — 8.14.1

References

Advisories & Patches

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

Exploits

https://hackerone.com/reports/3168039

Other References

http://www.openwall.com/lists/oss-security/2025/06/04/2

Frequently Asked Questions

What is CVE-2025-5399? +

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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2025-5399? +

CVE-2025-5399 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-5399? +

CVE-2025-5399 affects products from haxx, specifically: curl. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-5399? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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