openssl_encrypt versions before 1.4.6 contain a key derivation flaw in sequential XOR composition mode where the last stage cancels out during key generation. When configured with a single KDF and no prior hashing stage, attackers can bypass memory-hard key derivation and perform offline password cracking at SHA-256 speed instead of the configured KDF cost.
https://www.vulncheck.com/advisories/openssl-encrypt-before-kdf-bypass-via-sequential-xor
https://github.com/jahlives/openssl_encrypt/security/advisories/GHSA-vxf9-vwp6-2w43
Published: 2026-08-17
Updated: 2026-08-17
Base Score: 4.9
Vector: CVSS2#AV:L/AC:L/Au:N/C:C/I:N/A:N
Severity: Medium
Base Score: 6.2
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Severity: Medium
Base Score: 6.9
Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Severity: Medium