OpenPGP.js is a JavaScript implementation of the OpenPGP protocol. In affected versions OpenPGP Cleartext Signed Messages are cryptographically signed messages where the signed text is readable without special tools. These messages typically contain a "Hash: ..." header declaring the hash algorithm used to compute the signature digest. OpenPGP.js up to v5.9.0 ignored any data preceding the "Hash: ..." texts when verifying the signature. As a result, malicious parties could add arbitrary text to a third-party Cleartext Signed Message, to lead the victim to believe that the arbitrary text was signed. A user or application is vulnerable to said attack vector if it verifies the CleartextMessage by only checking the returned `verified` property, discarding the associated `data` information, and instead _visually trusting_ the contents of the original message. Since `verificationResult.data` would always contain the actual signed data, users and apps that check this information are not vulnerable. Similarly, given a CleartextMessage object, retrieving the data using `getText()` or the `text` field returns only the contents that are considered when verifying the signature. Finally, re-armoring a CleartextMessage object (using `armor()` will also result in a "sanitised" version, with the extraneous text being removed. This issue has been addressed in version 5.10.1 (current stable version) which will reject messages when calling `openpgp.readCleartextMessage()` and in version 4.10.11 (legacy version) which will will reject messages when calling `openpgp.cleartext.readArmored()`. Users are advised to upgrade. Users unable to upgrade should check the contents of `verificationResult.data` to see what data was actually signed, rather than visually trusting the contents of the armored message.

A cryptographic issue in OpenPGP.js <=4.2.0 allows an attacker who is able provide forged messages and gain feedback about whether decryption of these messages succeeded to conduct an invalid curve attack in order to gain the victim's ECDH private key.

Improper Verification of a Cryptographic Signature in OpenPGP.js <=4.1.2 allows an attacker to pass off unsigned data as signed.

Improper Verification of a Cryptographic Signature in OpenPGP.js <=4.1.2 allows an attacker to forge signed messages by replacing its signatures with a "standalone" or "timestamp" signature.

s2k.js in OpenPGP.js will decrypt arbitrary messages regardless of passphrase for crafted PGP keys which allows remote attackers to bypass authentication if message decryption is used as an authentication mechanism via a crafted symmetrically encrypted PGP message.