CVE-2026-63761 Vulnerability Analysis & Exploit Details

CVE-2026-63761 Vulnerability Summary

CVE-2026-63761: SurrealDB before 3.1.0 silently substitutes the ES384 algorithm when a JWT access method is configured with ALGORITHM ES512 (DEFINE ACCESS ... TYPE JWT ALGORITHM ES512), because the underlying jsonwebtoken crate (v10.x) has no ES512 variant and the mapping defaults to ES384 without any error, warning, or log message. Users who supply the correct P-521 key for ES512 experience authentication handshake failures due to the curve mismatch with ES384 (which expects P-384), and tokens are rejected by external systems expecting genuine ES512 signatures. The flaw cannot be used to forge tokens or compromise data confidentiality or integrity, as ES384 remains cryptographically strong.

CVE-2026-63761 References

External References

• https://github.com/surrealdb/surrealdb/security/advisories/GHSA-fwg2-gr34-q3w8
• https://www.vulncheck.com/advisories/surrealdb-before-algorithm-downgrade-via-es512

CWE Common Weakness Enumeration

CAPEC Common Attack Pattern Enumeration and Classification

• Encryption Brute Forcing CAPEC-20 An attacker, armed with the cipher text and the encryption algorithm used, performs an exhaustive (brute force) search on the key space to determine the key that decrypts the cipher text to obtain the plaintext.
• Creating a Rogue Certification Authority Certificate CAPEC-459 An adversary exploits a weakness resulting from using a hashing algorithm with weak collision resistance to generate certificate signing requests (CSR) that contain collision blocks in their "to be signed" parts. The adversary submits one CSR to be signed by a trusted certificate authority then uses the signed blob to make a second certificate appear signed by said certificate authority. Due to the hash collision, both certificates, though different, hash to the same value and so the signed blob works just as well in the second certificate. The net effect is that the adversary's second X.509 certificate, which the Certification Authority has never seen, is now signed and validated by that Certification Authority.
• Signature Spoof CAPEC-473 An attacker generates a message or datablock that causes the recipient to believe that the message or datablock was generated and cryptographically signed by an authoritative or reputable source, misleading a victim or victim operating system into performing malicious actions.
• Signature Spoofing by Improper Validation CAPEC-475 An adversary exploits a cryptographic weakness in the signature verification algorithm implementation to generate a valid signature without knowing the key.
• Cryptanalysis of Cellular Encryption CAPEC-608 The use of cryptanalytic techniques to derive cryptographic keys or otherwise effectively defeat cellular encryption to reveal traffic content. Some cellular encryption algorithms such as A5/1 and A5/2 (specified for GSM use) are known to be vulnerable to such attacks and commercial tools are available to execute these attacks and decrypt mobile phone conversations in real-time. Newer encryption algorithms in use by UMTS and LTE are stronger and currently believed to be less vulnerable to these types of attacks. Note, however, that an attacker with a Cellular Rogue Base Station can force the use of weak cellular encryption even by newer mobile devices.
• Rooting SIM Cards CAPEC-614 SIM cards are the de facto trust anchor of mobile devices worldwide. The cards protect the mobile identity of subscribers, associate devices with phone numbers, and increasingly store payment credentials, for example in NFC-enabled phones with mobile wallets. This attack leverages over-the-air (OTA) updates deployed via cryptographically-secured SMS messages to deliver executable code to the SIM. By cracking the DES key, an attacker can send properly signed binary SMS messages to a device, which are treated as Java applets and are executed on the SIM. These applets are allowed to send SMS, change voicemail numbers, and query the phone location, among many other predefined functions. These capabilities alone provide plenty of potential for abuse.
• Cryptanalysis CAPEC-97 Cryptanalysis is a process of finding weaknesses in cryptographic algorithms and using these weaknesses to decipher the ciphertext without knowing the secret key (instance deduction). Sometimes the weakness is not in the cryptographic algorithm itself, but rather in how it is applied that makes cryptanalysis successful. An attacker may have other goals as well, such as: Total Break (finding the secret key), Global Deduction (finding a functionally equivalent algorithm for encryption and decryption that does not require knowledge of the secret key), Information Deduction (gaining some information about plaintexts or ciphertexts that was not previously known) and Distinguishing Algorithm (the attacker has the ability to distinguish the output of the encryption (ciphertext) from a random permutation of bits).

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