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

What is CVE-2026-39833?

CVE-2026-39833 is a critical vulnerability in golang.org/x/crypto/ssh/agent, published on 22 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-862

Which versions are affected by CVE-2026-39833?

3 open source packages ship an affected version, including golang.org/x/crypto. It affects 1 product.

Products include Golang Crypto.

How do I fix CVE-2026-39833?

Upgrade golang.org/x/crypto to 0.52.0 or later.

Is CVE-2026-39833 being exploited?

There is no known exploitation of CVE-2026-39833 in the wild and no public exploit code.

Other vulnerabilities in golang.org/x/crypto/ssh/agent

• CVE-2026-46595 Invoking VerifiedPublicKeyCallback permissions skip enforcement in golang.org/x/crypto/ssh Critical 10.0
• CVE-2026-39830 Invoking client can cause server deadlock on unexpected responses in golang.org/x/crypto/ssh Critical 9.1
• CVE-2026-39831 Invoking bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh Critical 9.1
• CVE-2026-39832 Invoking agent constraints dropped when forwarding keys in golang.org/x/crypto/ssh/agent Critical 9.1
• CVE-2026-39834 Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh Critical 9.1

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-87176, AZL-87230, AZL-87320, AZL-87660, AZL-87684, AZL-88224 and 1120 more.