Session Resumption Vulnerability in Go's Crypto/TLS Library by Google
CVE-2025-68121

7.4HIGH

Key Information:

Vendor

Go Standard Library

Status
Crypto/tls
Vendor
CVE Published:
5 February 2026

What is CVE-2025-68121?

This vulnerability occurs during the process of session resumption in Go's Crypto/TLS library. If the ClientCAs or RootCAs fields of the configuration are altered between the initial and resumed handshake, it may lead to successful resumed handshakes under circumstances where they should have failed. This situation can be triggered through improper use of the Config.Clone method or the Config.GetConfigForClient function. As a result, a client may reconnect with a server it should not have, or a server may accept a session resumption request from a client that would have been denied during the original handshake.

Affected Version(s)

crypto/tls 0 < 1.24.13

crypto/tls 1.25.0-0 < 1.25.7

crypto/tls 1.26.0-rc.1 < 1.26.0-rc.3

References

https://groups.google.com/g/golang-announce/c/K09ubi9FQFk
https://go.dev/cl/737700
https://go.dev/issue/77217

CVSS V3.1

Score:
7.4
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Coia Prant (github.com/rbqvq)
Go Security Team
.