CVE-2026-39832 — Invoking agent constraints dropped when forwarding keys in golang.org/x/crypto/ssh/agent

Description (CNA)

When adding a key to a remote agent constraint extensions such as restrict-destination-v00@openssh.com were not serialized in the request. Destination restrictions were silently stripped when forwarding keys, allowing unrestricted use of the key on the remote host. The client now serializes all constraint extensions. Additionally, the in-memory keyring returned by NewKeyring() now rejects keys with unsupported constraint extensions instead of silently ignoring them.

Affected (CNA)

Vendor / product	Versions
golang.org/x/crypto / golang.org/x/crypto/ssh/agent	affected 0 before 0.52.0

CWE

No CWE identifiers supplied.

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

redhat-SADP

A flaw was found in golang.org/x/crypto/ssh/agent. When a key was added to a remote agent, security restrictions, known as constraint extensions, were not properly processed during the request. This allowed these restrictions to be silently removed when keys were forwarded, leading to the unrestricted use of the key on the remote host. This vulnerability could enable an attacker to bypass intended security controls and perform unauthorized actions.