CVE-2026-74871: openssl_encrypt before 1.4.6 KDF Bypass via Sequential-XOR
opensslencrypt 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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
openssl_encrypt (OpenSSL extension/openssl_encrypt)to a version that resolves this vulnerability.Fixed in 1.4.6
Event History
Frequently Asked Questions
What is the severity of CVE-2026-74871?
CVE-2026-74871 has a medium severity rating of 6.2.
How do I fix CVE-2026-74871?
To fix CVE-2026-74871, upgrade to OpenSSL version 1.4.6 or later.
What does CVE-2026-74871 exploit?
CVE-2026-74871 exploits a key derivation flaw in OpenSSL's sequential XOR composition mode.
What are the potential consequences of CVE-2026-74871?
The potential consequences include bypassing memory-hard key derivation and performing offline password cracking.
Which versions of OpenSSL are affected by CVE-2026-74871?
OpenSSL versions before 1.4.6 are affected by CVE-2026-74871.