Vulnerability · Published Jun 7, 2025 · Assigned by curl
CVE-2025-5399WebSocket endless loop
High 7.5
In plain English
A high-severity security flaw in curl from curl. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 1.4% (higher than 73% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)1.4%top 26.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | curl | 8.14.1-r0 | ALPINE-CVE-2025-5399 |
| Alpine:v3.21 | curl | 8.14.1-r0 | ALPINE-CVE-2025-5399 |
| Alpine:v3.22 | curl | 8.14.1-r0 | ALPINE-CVE-2025-5399 |
| Alpine:v3.23 | curl | 8.14.1-r0 | ALPINE-CVE-2025-5399 |
| Alpine:v3.24 | curl | 8.14.1-r0 | ALPINE-CVE-2025-5399 |
| Debian:13 | curl | 8.14.1-1 | DEBIAN-CVE-2025-5399 |
| Debian:14 | curl | 8.14.1-1 | DEBIAN-CVE-2025-5399 |