What’s Vulnerable › Vulnerabilities

CVE-2026-39833: Invoking key constraints not enforced in golang.org/x/crypto/ssh/agent

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-22 · updated 2026-08-11
• Weakness: CWE-862

Description

The in-memory keyring returned by NewKeyring() silently accepted keys with the ConfirmBeforeUse constraint but never enforced it. The key would sign without any confirmation prompt, with no indication to the caller that the constraint was not in effect. NewKeyring() now returns an error when unsupported constraints are requested.

Affected products

• golang.org/x/crypto/ssh: before 0.52.0 — fixed in 0.52.0
• Golang.Org/X/Crypto: before 0.52.0 — fixed in 0.52.0

How to fix

Upgrade to a fixed version: golang.org/x/crypto/ssh 0.52.0; Golang.Org/X/Crypto 0.52.0. Check the vendor advisory for mitigations.

References

• https://go.dev/cl/778642
• https://go.dev/issue/79436
• https://groups.google.com/g/golang-announce/c/a082jnz-LvI
• https://pkg.go.dev/vuln/GO-2026-5005

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