CVE-2026-84971 Persistent client crash loop via undersized FLE2 insert-update ciphertext in decryption path

Improper handling of an unexpected value size in the decryption path of a client-side encryption library can cause a failed internal check that terminates the process using the library. A party able to place a suitably formed encrypted value where an application will decrypt it, or able to contro...

Persistent client crash loop via undersized FLE2 insert-update ciphertext in decryption path

Improper handling of an unexpected value size in the decryption path of a client-side encryption library can cause a failed internal check that terminates the process using the library. A party able to place a suitably formed encrypted value where an application will decrypt it, or able to contro...

CVE-2026-84971 Persistent client crash loop via undersized FLE2 insert-update ciphertext in decryption path

Improper handling of an unexpected value size in the decryption path of a client-side encryption library can cause a failed internal check that terminates the process using the library. A party able to place a suitably formed encrypted value where an application will decrypt it, or able to contro...

CVE-2026-84971

CVE-2026-84971 affects MongoDB's client-side encryption library (mongocrypt) . The root cause is improper handling of an undersized FLE2 insert-update ciphertext in the decryption path, which triggers a failed internal check that terminates the process using the library, causing a persistent clie...