oven-sh/bun · error · TypeError

SUITE_B_LOS_NOT_ALLOWED

SUITE_B_LOS_NOT_ALLOWED

Error message

SUITE_B_LOS_NOT_ALLOWED

What it means

CertError::SUITE_B_LOS_NOT_ALLOWED maps BoringSSL X509_V_ERR_SUITE_B_LOS_NOT_ALLOWED (verify code 60). The configured Suite B level of security (LOS) does not allow a curve used in the chain: P-384 keys are outside the 128-bit LOS profile, and P-256 outside the 192-bit one. Message: "Suite B: curve not allowed for this LOS".

Source

Thrown at src/http/error.rs:239

    #[error("APPLICATION_VERIFICATION")]
    APPLICATION_VERIFICATION,
    #[error("UNSUPPORTED_CONSTRAINT_TYPE")]
    UNSUPPORTED_CONSTRAINT_TYPE,
    #[error("UNSUPPORTED_CONSTRAINT_SYNTAX")]
    UNSUPPORTED_CONSTRAINT_SYNTAX,
    #[error("UNSUPPORTED_NAME_SYNTAX")]
    UNSUPPORTED_NAME_SYNTAX,
    #[error("CRL_PATH_VALIDATION_ERROR")]
    CRL_PATH_VALIDATION_ERROR,
    #[error("SUITE_B_INVALID_VERSION")]
    SUITE_B_INVALID_VERSION,
    #[error("SUITE_B_INVALID_ALGORITHM")]
    SUITE_B_INVALID_ALGORITHM,
    #[error("SUITE_B_INVALID_CURVE")]
    SUITE_B_INVALID_CURVE,
    #[error("SUITE_B_INVALID_SIGNATURE_ALGORITHM")]
    SUITE_B_INVALID_SIGNATURE_ALGORITHM,
    #[error("SUITE_B_LOS_NOT_ALLOWED")]
    SUITE_B_LOS_NOT_ALLOWED,
    #[error("SUITE_B_CANNOT_SIGN_P_384_WITH_P_256")]
    SUITE_B_CANNOT_SIGN_P_384_WITH_P_256,
    #[error("HOSTNAME_MISMATCH")]
    HOSTNAME_MISMATCH,
    #[error("EMAIL_MISMATCH")]
    EMAIL_MISMATCH,
    #[error("IP_ADDRESS_MISMATCH")]
    IP_ADDRESS_MISMATCH,
    #[error("INVALID_CALL")]
    INVALID_CALL,
    #[error("STORE_LOOKUP")]
    STORE_LOOKUP,
    #[error("NAME_CONSTRAINTS_WITHOUT_SANS")]
    NAME_CONSTRAINTS_WITHOUT_SANS,
    #[error("UNKNOWN_CERTIFICATE_VERIFICATION_ERROR")]
    UNKNOWN_CERTIFICATE_VERIFICATION_ERROR,
}

View on GitHub (pinned to 8c5296ac45)

Solutions

1. Decide the target LOS, then make every chain certificate use that curve: P-256 for 128-bit, P-384 for 192-bit
2. Align the flag with reality: set X509_V_FLAG_SUITE_B_128_LOS for P-256 chains, _192_LOS for P-384
3. Audit for mixed curves: openssl x509 -noout -text | grep 'ASN1 OID' across the chain

Example fix

# before: 128-bit LOS flag, chain contains P-384 intermediates
verify_flags = suiteb_128

# after: consistent profile - all P-256 with 128-bit LOS
verify_flags = suiteb_128   # chain: prime256v1 throughout

// Assert one curve strength throughout the chain matching the intended Suite B LOS
import tls from "node:tls";
import { X509Certificate } from "node:crypto";
export function chainMatchesLos(host, los /* 'P-256' | 'P-384' */, port = 443) {
  return new Promise((resolve, reject) => {
    const s = tls.connect({ host, port, servername: host, rejectUnauthorized: false }, () => {
      let c = s.getPeerCertificate(true), ok = true;
      do { ok = ok && new X509Certificate(c.raw).keyObject.export({ format: "jwk" }).crv === los; }
      while (c.issuerCertificate && (c = c.issuerCertificate) && !Object.is(c, s.getPeerCertificate(true)));
      s.end(); resolve(ok);
    });
    s.on("error", reject);
  });
}

export function isSuiteBLosNotAllowed(e): e is Error & { code: "SUITE_B_LOS_NOT_ALLOWED" } {
  return e instanceof Error && (e as any).code === "SUITE_B_LOS_NOT_ALLOWED";
}

try {
  await fetch(url);
} catch (e) {
  if (e?.code === "SUITE_B_LOS_NOT_ALLOWED") {
    // curve strength doesn't match the enabled LOS flag - align chain and flag
    alignSuiteBProfile(url);
  } else throw e;
}

When it happens

Trigger: Verifier sets X509_V_FLAG_SUITE_B_128_LOS but the chain contains a P-384 certificate (or _192_LOS with a P-256 certificate). Suite B pins one curve strength per profile; mixing fails.

Common situations: Teams 'upgrading' half a chain to P-384 while the gateway runs the 128-bit flag; flag misconfiguration (192 selected where 128 intended) on defense-grade proxies; inconsistent policy between two enforcing middleboxes in the path.

Related errors

• SUITE_B_INVALID_VERSION
• SUITE_B_INVALID_CURVE
• SUITE_B_CANNOT_SIGN_P_384_WITH_P_256
• SUITE_B_INVALID_ALGORITHM
• SUITE_B_INVALID_SIGNATURE_ALGORITHM

AI-assisted analysis of oven-sh/bun@8c5296ac45 (2026-08-16). Data as JSON: /api/errors/b7e1c28540831af0. Report an issue: GitHub.