[Go 1.24.0] CVE-2026-39832: ssh/agent: reject keys with unsupported confirm constraint - #11
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The in-memory keyring supports the "lifetime" constraint but does not implement the "confirm" constraint. Previously, keyring.Add silently ignored ConfirmBeforeUse: the key was stored, advertised through List, and used for signing without any interactive confirmation, potentially misleading callers into believing this security measure was enforced. Return an error when ConfirmBeforeUse is set instead of silently downgrading the caller's security expectations. Implementing real confirm-before-use in an in-memory library keyring is infeasible (there is no UI or confirmation callback), so failing closed is the correct behavior; adding actual confirm support would require an API addition and is out of scope. This is a deliberate behavior change: keyring.Add previously accepted and ignored ConfirmBeforeUse and now returns an error. This change also updates the keyring doc comments to document the supported constraints. This issue was found during a security audit by NCC Group Cryptography Services, sponsored by Teleport. Fixes CVE-2026-39833 Updates golang/go#47533 Fixes golang/go#79436 Change-Id: I1b3a286f0c1e4a4e08ac37109f7e491692ca90ae Reviewed-on: https://go-review.googlesource.com/c/crypto/+/778642 Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Reviewed-by: Neal Patel <nealpatel@google.com> Reviewed-by: Neal Patel <neal@golang.org> Auto-Submit: Neal Patel <nealpatel@google.com> LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
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Process
Conflicts
ssh/agent/keyring.go: Patch expected ConstraintExtensions rejection check to already exist — v0.48.0 does not have it. User applied ConfirmBeforeUse check manually.ssh/agent/keyring_test.go: Patch expected TestAddKeyWithConstraintExtensions test — not present in v0.48.0. User added new test manually.Patch Source
https://go-review.googlesource.com/changes/crypto~778642/revisions/3/patch?download&raw
v0.48.0-GO-2026-5006-0.patch
Verification
go vet ./...: passed