CVE-2025-61778: akkadotnet akka.net · Authentication Bypass by Spoofing
Affects akkadotnet akka.netSource CVE Database V5
Not known to be exploited · CVSS 9.3 Critical.
Data as of 26 Oct 2026, 06:26 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 23% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 6 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.
What to do
AI-suggested
The primary mitigation is to upgrade all Akka.NET deployments to version 1.5.52 or later, which enforces mutual TLS by default and introduces fail-fast checks for private key validity. Organizations should audit their Akka.NET usage to identify affected versions and ensure timely patching. Network administrators should verify that TLS is properly configured with mutual authentication enabled, ensuring both client and server certificates are validated against trusted certificate authorities. Avoid exposing Akka.NET services directly to public networks; instead, restrict access via VPNs or secure internal networks with strict firewall rules. Implement network segmentation to isolate Akka.NET clusters from untrusted zones. Monitor network traffic for anomalous connections to Akka.NET ports and enable logging to detect unauthorized access attempts. Conduct regular security assessments and penetration testing focused on Akka.NET components. Additionally, review certificate management practices to ensure private keys are securely stored and rotated regularly. Educate development and operations teams about the importance of mutual TLS and secure configuration to prevent similar issues in the future.
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.
References
- github.com/akkadotnet/akka.net/security/advisories/GHSA-jhpv-4q4f-43g5 (opens in a new tab)
- github.com/akkadotnet/akka.net/pull/7847 (opens in a new tab)
- github.com/akkadotnet/akka.net/pull/7851 (opens in a new tab)
- getakka.net/articles/remoting/security.html (opens in a new tab)
- github.com/akkadotnet/akka.net/releases/tag/1.5.52 (opens in a new tab)