Vulnerability · Published Oct 6, 2025 · Assigned by GitHub_M
CVE-2025-61778Akka.Remote TLS did not properly implement certificate-based authentication
Critical 9.3
In plain English
A critical-severity authentication bypass by spoofing in akka.net from akkadotnet. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Akka.NET is a .NET port of the Akka project from the Scala / Java community. In all versions of Akka.Remote from v1.2.0 to v1.5.51, TLS could be enabled via our `akka.remote.dot-netty.tcp` transport and this would correctly enforce private key validation on the server-side of inbound connections. Akka.Remote, however, never asked the outbound-connecting client to present ITS certificate - therefore it's possible for untrusted parties to connect to a private key'd Akka.NET cluster and begin communicating with it without any certificate. The issue here is that for certificate-based authentication to work properly, ensuring that all members of the Akka.Remote network are secured with the same private key, Akka.Remote needed to implement mutual TLS. This was not the case before Akka.NET v1.5.52. Those who run Akka.NET inside a private network that they fully control or who were never using TLS in the first place are now affected by the bug. However, those who use TLS to secure their networks must upgrade to Akka.NET V1.5.52 or later. One patch forces "fail fast" semantics if TLS is enabled but the private key is missing or invalid. Previous versions would only check that once connection attempts occurred. The second patch, a critical fix, enforces mutual TLS (mTLS) by default, so both parties must be keyed using the same certificate. As a workaround, avoid exposing the application publicly to avoid the vulnerability having a practical impact on one's application. However, upgrading to version 1.5.52 is still recommended by the maintainers.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| NuGet | akka.cluster | 1.5.52 | GHSA-jhpv-4q4f-43g5 |
| NuGet | akka.remote | 1.5.52 | GHSA-jhpv-4q4f-43g5 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| akkadotnet | akka.net | >= 1.2.0, < 1.5.52 |
Weakness: CWE-290, CWE-295, CWE-306 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
References
- https://github.com/akkadotnet/akka.net/security/advisories/GHSA-jhpv-4q4f-43g5 x_refsource_CONFIRM
- https://github.com/akkadotnet/akka.net/pull/7847 x_refsource_MISC
- https://github.com/akkadotnet/akka.net/pull/7851 x_refsource_MISC
- https://getakka.net/articles/remoting/security.html x_refsource_MISC
- https://github.com/akkadotnet/akka.net/releases/tag/1.5.52 x_refsource_MISC