CVE-2020-5403 DoS Via Malformed URL with Reactor Netty HTTP Server
Attackers can cause premature connection closure via malformed URLs in Reactor Netty, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2020-5403?
CVE-2020-5403 is a medium-severity denial of service vulnerability in Pivotal Reactor Netty, published on 3 Mar 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Reactor Netty HttpServer, versions 0.9.3 and 0.9.4, is exposed to a URISyntaxException that causes the connection to be closed prematurely instead of producing a 400 response.
Which versions are affected by CVE-2020-5403?
2 open source packages ship an affected version, including io.projectreactor.netty:reactor-netty-http. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
io.projectreactor.netty:reactor-netty-http Maven | From 0.9.3 | 0.9.5 |
io.projectreactor.netty:reactor-netty-http Maven | From 0.9.3 | 0.9.5 |
Products include Broadcom Reactor Netty.
How do I fix CVE-2020-5403?
Upgrade io.projectreactor.netty:reactor-netty-http to 0.9.5 or later.
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-2020-5403 being exploited?
There is no known exploitation of CVE-2020-5403 in the wild and no public exploit code.
Other vulnerabilities in Pivotal Reactor Netty
- CVE-2023-34062 In Reactor Netty HTTP Server a malicious user can send a request using a specially crafted URL that can lead to a directory traversal attack
- CVE-2019-11284 Reactor Netty authentication leak in redirects
- CVE-2020-5404 Authentication Leak On Redirect With Reactor Netty HttpClient
- CVE-2026-47848 Reactor Netty WebSocket Client Leaks Credentials On Redirect
- CVE-2026-47844 Reactor Netty HTTP Server Leaks Exception Details
Sources
Also known as GHSA-hp5x-rqf7-43vf.