[Go 1.18] CVE-2026-39832: ssh/agent: reject keys with unsupported confirm constraint

[Atharva-Shinde]

Process

# branch_setup.py — checked out upstream/sustaining-v0.24.0
# git am failed — patch context mismatch, user resolved manually

Conflicts

• ssh/agent/keyring.go: Patch expected ConstraintExtensions rejection check to already exist — v0.24.0 does not have it. User applied ConfirmBeforeUse check manually.
• ssh/agent/keyring_test.go: Patch expected TestAddKeyWithConstraintExtensions test — not present in v0.24.0. User added new test manually.
• ssh/test/agent_unix_test.go: Context mismatch at line 24 — user resolved manually.

Patch Source

https://go-review.googlesource.com/changes/crypto~778642/revisions/3/patch?download&raw

v0.24.0-GO-2026-5006-0.patch

Verification

Runtime gates: none

Unit tests output

crypto git:(sustaining-v0.24.0) go test ./...
# golang.org/x/crypto/ssh
ssh/server_test.go:12:2: package slices is not in GOROOT (/Users/atharva/.gvm/gos/go1.18/src/slices)
FAIL    golang.org/x/crypto/ssh [setup failed]
# golang.org/x/crypto/internal/testenv
internal/testenv/exec.go:96:30: undefined: Sigquit
# golang.org/x/crypto/sha3 [golang.org/x/crypto/sha3.test]
sha3/xor.go:25:10: undefined: subtle.XORBytes
ok      golang.org/x/crypto/acme        14.340s
ok      golang.org/x/crypto/acme/autocert       5.980s
?       golang.org/x/crypto/acme/autocert/internal/acmetest  [no test files]
?       golang.org/x/crypto/acme/internal/acmeprobe [no test files]
ok      golang.org/x/crypto/argon2      0.561s
ok      golang.org/x/crypto/bcrypt      2.314s
ok      golang.org/x/crypto/blake2b     3.153s
ok      golang.org/x/crypto/blake2s     2.721s
ok      golang.org/x/crypto/blowfish    1.418s
ok      golang.org/x/crypto/bn256       3.664s
ok      golang.org/x/crypto/cast5       2.478s
ok      golang.org/x/crypto/chacha20    2.281s
ok      golang.org/x/crypto/chacha20poly1305    4.018s
ok      golang.org/x/crypto/cryptobyte  4.469s
?       golang.org/x/crypto/cryptobyte/asn1     [no test files]
ok      golang.org/x/crypto/curve25519  4.912s
ok      golang.org/x/crypto/curve25519/internal/field6.738s
ok      golang.org/x/crypto/ed25519     6.181s
ok      golang.org/x/crypto/hkdf        5.746s
ok      golang.org/x/crypto/internal/alias      5.345s
ok      golang.org/x/crypto/internal/poly1305   5.754s
ok      golang.org/x/crypto/internal/wycheproof 7.662s
ok      golang.org/x/crypto/md4 6.164s
ok      golang.org/x/crypto/nacl/auth   6.745s
ok      golang.org/x/crypto/nacl/box    6.079s
ok      golang.org/x/crypto/nacl/secretbox      6.124s
ok      golang.org/x/crypto/nacl/sign   6.127s
ok      golang.org/x/crypto/ocsp        6.146s
ok      golang.org/x/crypto/openpgp     6.747s
ok      golang.org/x/crypto/openpgp/armor       5.230s
ok      golang.org/x/crypto/openpgp/clearsign   10.474s
ok      golang.org/x/crypto/openpgp/elgamal     5.761s
ok      golang.org/x/crypto/openpgp/packet      5.714s
ok      golang.org/x/crypto/openpgp/s2k 7.039s
ok      golang.org/x/crypto/otr 5.360s
ok      golang.org/x/crypto/pbkdf2      4.987s
ok      golang.org/x/crypto/pkcs12      5.235s
ok      golang.org/x/crypto/pkcs12/internal/rc2 5.439s
ok      golang.org/x/crypto/ripemd160   5.804s
ok      golang.org/x/crypto/salsa20     5.749s
ok      golang.org/x/crypto/salsa20/salsa       5.658s
ok      golang.org/x/crypto/scrypt      5.336s
FAIL    golang.org/x/crypto/sha3 [build failed]
--- FAIL: TestAgent (0.03s)
    client_test.go:150: insert(*dsa.PrivateKey): agent: failure
--- FAIL: TestLockOpenSSHAgent (0.02s)
    client_test.go:461: Add: agent: failure
    client_test.go:466: Want 2 keys, got [ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCe6jMoy1xCQgiZkZJ7gi6NLj4uRqz2OaUGK/OJYZTfBqK+SlS9iymAluHu9K+cc4+0qxx0gn7dRTJWINSgzvca6ayYe995EKgD1hE5krh9BH0bRrXB+hGqyslcZOgLNO+v8jYojClQbRtET2tS+xb4k33GCuL5wgla2790ZgOQgs7huQUjG0S8c1W+EYt6fI4cWE/DeEBnv9sqryS8rOb0PbM6WUd7XBadwySFWYQUX0ei56GNt12Z4gADEGlFQV/OnV0PvnTcAMGUl0rfToPgJ4jgogWKoTVWuZ9wyA/x+2LRLRvgm2a969ig937/AH0i0Wq+FzqfK7EXQ99Yf5K/ comment 1]
    client_test.go:507: Want 1 keys, got []
2026/07/31 11:43:42 agent 23: agent: incorrect passphrase
2026/07/31 11:43:42 agent 25: agent: confirm before use constraint is not supported
FAIL
FAIL    golang.org/x/crypto/ssh/agent   4.935s
ok      golang.org/x/crypto/ssh/internal/bcrypt_pbkdf5.219s
ok      golang.org/x/crypto/ssh/knownhosts      5.078s
FAIL    golang.org/x/crypto/ssh/test [build failed]
ok      golang.org/x/crypto/tea 4.627s
ok      golang.org/x/crypto/twofish     5.001s
ok      golang.org/x/crypto/x509roots/nss       4.987s
ok      golang.org/x/crypto/xtea        5.091s
ok      golang.org/x/crypto/xts 5.439s