gchq/CyberChef · error · OperationError

${err.toString()}

Error message

${err.toString()}

What it means

Generic catch-all thrown by BSONDeserialise.run when the underlying bson deserialize() throws on the input bytes. BSON is a strict binary format with length-prefixed documents, typed fields, and terminator bytes; any structural defect (truncation, bad length prefix, unknown/invalid element type, bad UTF-8 string) causes the library to throw, and the original Error.toString() is forwarded verbatim as the OperationError message.

Source

Thrown at src/core/operations/BSONDeserialise.mjs:43

        this.infoURL = "https://wikipedia.org/wiki/BSON";
        this.inputType = "ArrayBuffer";
        this.outputType = "string";
        this.args = [];
    }

    /**
     * @param {ArrayBuffer} input
     * @param {Object[]} args
     * @returns {string}
     */
    run(input, args) {
        if (!input.byteLength) return "";

        try {
            const data = deserialize(new Uint8Array(input));
            return JSON.stringify(data, null, 2);
        } catch (err) {
            throw new OperationError(err.toString());
        }
    }

}

export default BSONDeserialise;

View on GitHub (pinned to 4290ea7539)

Solutions

1. Confirm the input is genuine BSON binary produced by a BSON serialiser.
2. If you have JSON text, use BSONSerialise's inverse or a JSON parser instead.
3. Inspect the forwarded Error.toString() message for the specific BSON defect.
4. Re-serialize the source document and re-copy the full buffer.

Example fix

// before - feeding JSON text
chef.bSONDeserialise('{"a":1}');

// after - feeding BSON bytes from BSONSerialise
const bsonBytes = chef.bSONSerialise('{"a":1}');
chef.bSONDeserialise(bsonBytes);

function looksLikeBSON(buf) {
  if (!(buf instanceof ArrayBuffer) || buf.byteLength < 5) return false;
  const dv = new DataView(buf);
  const docLen = dv.getInt32(0, true);
  return docLen >= 5 && docLen <= buf.byteLength;
}

function isLikelyBSON(buf) {
  if (!(buf instanceof ArrayBuffer) || buf.byteLength < 5) return false;
  const dv = new DataView(buf);
  const docLen = dv.getInt32(0, true);
  return docLen >= 5 && docLen <= buf.byteLength;
}

try {
  chef.bSONDeserialise(buf);
} catch (e) {
  if (/bson|truncat|length|type/i.test(e.message)) {
    throw new Error(`Not valid BSON: ${e.message}`);
  }
  throw e;
}

When it happens

Trigger: Feeding non-BSON bytes (e.g. JSON text, MessagePack, or random binary), a truncated BSON document, a document whose declared length does not match the buffer, or a string field with invalid UTF-8.

Common situations: Piping JSON text into BSONDeserialise by mistake; copy-paste truncating the binary buffer; upstream 'From Hex' with odd-length or corrupted hex.

Related errors

• ${err.toString()}
• Invalid hash
• Invalid UUID
• ${err}
• ${error}

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/8479ab3dc511aaeb. Report an issue: GitHub.