Missing Server Signature Verification in Utils.readChallengeTx in js-stellar-sdk

CVE-2021-32738 · MEDIUM Severity

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

js-stellar-sdk is a Javascript library for communicating with a Stellar Horizon server. The `Utils.readChallengeTx` function used in SEP-10 Stellar Web Authentication states in its function documentation that it reads and validates the challenge transaction including verifying that the `serverAccountID` has signed the transaction. In js-stellar-sdk before version 8.2.3, the function does not verify that the server has signed the transaction. Applications that also used `Utils.verifyChallengeTxThreshold` or `Utils.verifyChallengeTxSigners` to verify the signatures including the server signature on the challenge transaction are unaffected as those functions verify the server signed the transaction. Applications calling `Utils.readChallengeTx` should update to version 8.2.3, the first version with a patch for this vulnerability, to ensure that the challenge transaction is completely valid and signed by the server creating the challenge transaction.

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