CVE-2026-41715 is a medium-severity (CVSS 6.1) CWE-522 vulnerability in io.projectreactor.netty:reactor-netty. A fix is available for io.projectreactor.netty:reactor-netty — see the affected versions and patch details below.
Reactor Netty HTTP Client Leaks Credentials On Protocol Downgrade Redirect
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-41715.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
io.projectreactor.netty:reactor-netty☕io.projectreactor.netty:reactor-netty☕io.projectreactor.netty:reactor-netty☕io.projectreactor.netty:reactor-nettyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
In specific scenarios involving HTTP redirects from a secure to an insecure endpoint, the Reactor Netty HTTP client may leak credentials. In order for this to happen, the HTTP client must have been explicitly configured to follow redirects.
Affected versions: Reactor Netty 1.0.0 through 1.0.51; 1.1.0 through 1.1.35; 1.2.0 through 1.2.17; 1.3.0 through 1.3.5.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.projectreactor.netty:reactor-netty | ≥ 1.3.0&&< 1.3.6 | 1.3.6io.projectreactor.netty:reactor-netty:1.3.6 |
| ☕Maven | io.projectreactor.netty:reactor-netty | ≥ 1.2.0&&< 1.2.18 | 1.2.18io.projectreactor.netty:reactor-netty:1.2.18 |
| ☕Maven | io.projectreactor.netty:reactor-netty | ≥ 1.1.0 | No fix |
| ☕Maven | io.projectreactor.netty:reactor-netty | ≥ 1.0.0 | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.projectreactor.netty:reactor-netty, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.projectreactor.netty:reactor-netty to 1.3.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41715 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Red Hat ships reactor-netty as a dependency in Red Hat JBoss Fuse 7 and Red Hat JBoss EAP Expansion Pack (XP). This vulnerability is only exploitable when the Reactor Netty HTTP client is explicitly configured to follow redirects, which is not the default behavior.
Do not configure the Reactor Netty HTTP client to automatically follow redirects, or ensure that redirect following is restricted to same-scheme (HTTPS-to-HTTPS) redirects only.Source: Red Hat security advisory for CVE-2026-41715 (CC BY 4.0)
Frequently Asked Questions
Is CVE-2026-41715 in your dependencies?
Find it across Maven, including transitive dependencies.