CVE-2025-61778
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-10-06

Last updated on: 2025-10-08

Assigner: GitHub, Inc.

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.
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Meta Information
Published
2025-10-06
Last Modified
2025-10-08
Generated
2026-05-07
AI Q&A
2025-10-06
EPSS Evaluated
2026-05-05
NVD
EUVD
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
akkadotnet akka.remote 1.5.52
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-306 The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
CWE-290 This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.
CWE-295 The product does not validate, or incorrectly validates, a certificate.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

CVE-2025-61778 is a critical security vulnerability in Akka.Remote (part of Akka.NET) versions 1.2.0 to 1.5.51 where TLS was enabled but mutual TLS (mTLS) was not enforced. While the server side validated its private key for inbound connections, the client side was never required to present its certificate. This allowed untrusted clients to connect to a private key-protected Akka.NET cluster without proper certificate-based authentication, enabling unauthorized communication within the cluster. The root cause was the lack of mutual TLS enforcement, which is necessary to ensure all nodes authenticate each other using certificates. The vulnerability was fixed in Akka.NET v1.5.52 by enforcing mutual TLS by default and adding fail-fast validation of private key access at startup to prevent misconfigurations and unauthorized access. [1, 3, 4]


How can this vulnerability impact me? :

This vulnerability can allow unauthorized and untrusted clients to connect to an Akka.NET cluster that is supposed to be protected by TLS, bypassing certificate-based authentication. This can lead to unauthorized access and communication within the cluster, potentially exposing sensitive data or allowing malicious actors to interfere with cluster operations. Additionally, if the private key is missing or inaccessible, the server may fail silently during TLS handshakes, causing operational issues. The impact is critical in environments where Akka.Remote is exposed or TLS is enabled without mutual authentication. Users running Akka.NET in private networks without TLS or those not exposing the application publicly are less affected, but upgrading to v1.5.52 or later is strongly recommended to mitigate these risks. [1, 3, 5]


How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:

The vulnerability undermines proper authentication and encryption controls required by common security standards and regulations such as GDPR and HIPAA. Without mutual TLS, unauthorized parties can access and communicate within the Akka.NET cluster, potentially leading to unauthorized data access or data breaches. This violates principles of data confidentiality and integrity mandated by these regulations. The fix in Akka.NET v1.5.52, which enforces mutual TLS by default, aligns with compliance requirements by ensuring strong authentication and encrypted communication between all cluster nodes. The maintainers recommend enabling mutual TLS especially in compliance-sensitive environments like PCI-DSS and HIPAA to meet regulatory security standards. [1]


How can this vulnerability be detected on my network or system? Can you suggest some commands?

Detection involves verifying the TLS and mutual TLS configuration of Akka.Remote nodes. You should check if your Akka.NET version is prior to 1.5.52 and if TLS is enabled without mutual TLS enforcement. On the system, ensure that the server has access to the private key by checking certificate permissions. For Windows, use commands like `icacls` to verify ACLs on private key files. Additionally, monitor for unexpected inbound connections from clients without certificates, which indicates lack of mutual TLS. There are no specific Akka.NET CLI commands provided, but general network scanning tools (e.g., `openssl s_client` to test TLS handshake and certificate presentation) can be used to test if mutual TLS is enforced. For example, you can attempt a TLS connection to the Akka.Remote endpoint and observe if the client certificate is requested or required. [1, 5]


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation steps include upgrading Akka.NET to version 1.5.52 or later, which enforces mutual TLS by default and validates private key access at startup. If upgrading is not immediately possible, avoid exposing Akka.Remote services publicly and restrict access to private networks secured by VPNs. Configure Akka.Remote to enable mutual TLS (`require-mutual-authentication = true`) and ensure `suppress-validation = false` to enforce proper certificate validation. Verify that the application has read access to the private key in the certificate store (on Windows, adjust ACLs using `icacls` if necessary). Use secure certificate management practices such as using the Windows Certificate Store or properly secured certificate files. Avoid using insecure settings like `suppress-validation = true` in production. [1, 2, 3, 5]


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