Vulnerability in Golang Go
CVE-2025-68121
During session resumption in crypto/tls, if the underlying Config has its ClientCAs or RootCAs fields mutated between the initial handshake and the resumed handshake, the resumed handshake may succeed when it should have failed. This may happen when a user calls Config.Clone and mutates the returned Config, or uses Config.GetConfigForClient. This can cause a client to resume a session with a server that it would not have resumed with during the initial handshake, or cause a server to resume a session with a client that it would not have resumed with during the initial handshake.
Vulnerability class: Improper Certificate Validation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.009 (56.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 57th percentile — 56.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.008 · newest: 0.009 · change: +0.001
Affected products
- Golang Go — versions 1.26.0
- Go Standard Library Crypto/tls — versions 0, 1.25.0-0, 1.26.0-rc.1
Weakness classification (CWE)
References
- groups.google.com/g/golang-announce/c/K09ubi9FQFk (Mailing List, Third Party Advisory)
- go.dev/cl/737700 (Patch)
- go.dev/issue/77217 (Exploit, Issue Tracking)
- pkg.go.dev/vuln/GO-2026-4337 (Vendor Advisory)
Frequently asked questions
- What is CVE-2025-68121?
- CVE-2025-68121 is a critical-severity vulnerability in Golang Go, classified under Improper Certificate Validation. CVSS score: 10.0/10. Published 2026-02-05.
- How severe is CVE-2025-68121?
- Critical severity. CVSS v3 base score is 10.0 out of 10.