CVE-2025-66560 Quarkus REST has potential worker thread starvation when HTTP connection is closed while waiting to write
Attackers can cause worker thread starvation and application unavailability by closing HTTP connections during response writes in Quarkus REST.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-66560?
CVE-2025-66560 is a medium-severity denial of service vulnerability in quarkusio quarkus, published on 7 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Quarkus is a Cloud Native, (Linux) Container First framework for writing Java applications. Prior to versions 3.31.0, 3.27.2, and 3.20.5, a vulnerability exists in the HTTP layer of Quarkus REST related to response handling. When a response is being written, the framework waits for previously written response chunks to be fully transmitted before proceeding. If the client connection is dropped during this waiting period, the associated worker thread is never released and becomes permanently blocked. Under sustained or repeated occurrences, this can exhaust the available worker threads, leading to degraded performance, or complete unavailability of the application. This issue has been patched in versions 3.31.0, 3.27.2, and 3.20.5. A workaround involves implementing a health check that monitors the status and saturation of the worker thread pool to detect abnormal thread retention early.
Weakness: CWE-770
Which versions are affected by CVE-2025-66560?
6 open source packages ship an affected version, including io.quarkus:quarkus-rest. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
io.quarkus:quarkus-rest Maven | All versions | 3.20.5 |
io.quarkus:quarkus-rest Maven | All versions | 3.20.5 |
io.quarkus:quarkus-rest Maven | From 3.21.0 | 3.27.2 |
io.quarkus:quarkus-rest Maven | From 3.21.0 | 3.27.2 |
io.quarkus:quarkus-rest Maven | From 3.30.0 | 3.31.0 |
io.quarkus:quarkus-rest Maven | From 3.30.0 | 3.31.0 |
Products include Quarkus Quarkus.
How do I fix CVE-2025-66560?
Upgrade io.quarkus:quarkus-rest to a fixed version for your release line: 3.20.5, 3.27.2 or 3.31.0.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-66560 being exploited?
There is no known exploitation of CVE-2025-66560 in the wild and no public exploit code.
Other vulnerabilities in quarkusio quarkus
- CVE-2022-4116 Code injection in quarkus dev ui config editor
- CVE-2022-2466 Quarkus does not terminate HTTP requests header context
- CVE-2024-12225 Io.quarkus:quarkus-security-webauthn: quarkus webauthn unexpected authentication bypass
- CVE-2026-39852 Quarkus authorization bypass via semicolon path normalization inconsistency
- CVE-2022-0981 Privilege escalation in quarkus
Sources
Also known as CLEANSTART-2026-NX85798, CLEANSTART-2026-PA41665, CLEANSTART-2026-VG40041, GHSA-5rfx-cp42-p624, MINI-chq2-xrqx-chq6, MINI-rqhh-7vg4-72cj.