Vulnerability in Curl
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.014 (70.9th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 71st percentile — 70.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.013 · newest: 0.014 · change: +0.001
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- 2499f714-1537-4658-8207-48ae4bb9eae9 (Vendor Advisory)
- 2499f714-1537-4658-8207-48ae4bb9eae9 (Vendor Advisory)
- 2499f714-1537-4658-8207-48ae4bb9eae9 (Exploit, Third Party Advisory, Issue Tracking)
- af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)
Frequently asked questions
- What is CVE-2025-5399?
- CVE-2025-5399 is a high-severity vulnerability in Curl, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 7.5/10. Published 2025-06-07.
- How severe is CVE-2025-5399?
- High severity. CVSS v3 base score is 7.5 out of 10.
- Is CVE-2025-5399 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.