{"record":{"id":"6e6057b604496e74","repo":"lcobucci/jwt","slug":"the-jwt-string-is-missing-the-signature-part","errorCode":null,"errorMessage":"The JWT string is missing the Signature part","messagePattern":"The JWT string is missing the Signature part","errorType":"exception","errorClass":"Lcobucci\\JWT\\Token\\InvalidTokenStructure","httpStatus":null,"severity":"error","filePath":"src/Token/Parser.php","lineNumber":39,"sourceCode":"\n    public function __construct(private Decoder $decoder)\n    {\n    }\n\n    public function parse(string $jwt): TokenInterface\n    {\n        [$encodedHeaders, $encodedClaims, $encodedSignature] = $this->splitJwt($jwt);\n\n        if ($encodedHeaders === '') {\n            throw InvalidTokenStructure::missingHeaderPart();\n        }\n\n        if ($encodedClaims === '') {\n            throw InvalidTokenStructure::missingClaimsPart();\n        }\n\n        if ($encodedSignature === '') {\n            throw InvalidTokenStructure::missingSignaturePart();\n        }\n\n        $header = $this->parseHeader($encodedHeaders);\n\n        return new Plain(\n            new DataSet($header, $encodedHeaders),\n            new DataSet($this->parseClaims($encodedClaims), $encodedClaims),\n            $this->parseSignature($encodedSignature),\n        );\n    }\n\n    /**\n     * Splits the JWT string into an array\n     *\n     * @param non-empty-string $jwt\n     *\n     * @return string[]\n     *","sourceCodeStart":21,"sourceCodeEnd":57,"githubUrl":"https://github.com/lcobucci/jwt/blob/375813049c24c7111bda8b6884c57b071ceb2fe7/src/Token/Parser.php#L21-L57","documentation":"Parser::parse() requires the third JWT segment (the Base64Url-encoded signature) to be non-empty. When it is empty, InvalidTokenStructure::missingSignaturePart() is thrown. A JWT shaped 'header.claims.' cannot be verified.","triggerScenarios":"Calling parse('header.claims.') or parse('header.claims') combined with a trailing dot — unsigned/truncated tokens; also JLS-style unsecured JWTs (alg:none) that this library does not accept.","commonSituations":"Tokens cut off when copied (signature is the last part and often truncated); unsigned JWTs issued by non-compliant services; tests using hand-made tokens without a signature.","solutions":["Use the full token exactly as issued — copy all three segments including the final signature","Reject tokens lacking a signature; this library requires signed tokens","Catch InvalidTokenStructure and return 'malformed token' to the client","If you need unsecured JWTs, use a different mechanism — lcobucci/jwt requires verification of the signature segment"],"exampleFix":"// before\n$token = $parser->parse($jwt); // jwt = 'aaa.bbb.'\n// after\n$segments = explode('.', $jwt);\nif (count($segments) !== 3 || in_array('', $segments, true)) {\n    throw new InvalidArgumentException('Malformed JWT: missing signature');\n}\n$token = $parser->parse($jwt);","handlingStrategy":"validation","validationCode":"$parts = explode('.', $jwt); if (count($parts) !== 3 || $parts[2] === '') { throw new InvalidArgumentException('JWT signature missing'); }","typeGuard":null,"tryCatchPattern":"try { $token = $parser->parse($jwt); } catch (Lcobucci\\JWT\\InvalidTokenStructure $e) { return error_401('Malformed token'); }","preventionTips":["Copy the complete token; signatures are at the end and most often truncated","Never accept unsigned (alg:none / missing signature) tokens","Store tokens in fixed-length-safe storage to avoid tail truncation"],"tags":["jwt","parser","signature","php"],"backgroundTag":"invalid-argument-format","analyzedSha":"375813049c24c7111bda8b6884c57b071ceb2fe7","analyzedAt":"2026-09-14T11:12:28.004Z","contentChangedAt":"2026-09-14T11:12:28.004Z","schemaVersion":2},"datasetVersion":"2026-09-16T09:17:16.951Z"}