CVE-2026-13608

A flaw was found in libcurl's SASL (Simple Authentication and Security Layer) negotiation for LDAP (Lightweight Directory Access Protocol) authentication when using the OpenLDAP backend. An incomplete handshake sequence can be misinterpreted as a successful cryptographic verification. A remote attacker, by performing a Man-in-the-Middle (MITM) attack, could inject a premature response to bypass complete peer validation, leading to an authentication bypass.

This Low impact flaw in libcurl's SASL negotiation for LDAP authentication could allow an attacker to bypass peer validation through a Man-in-the-Middle (MITM) attack. Exploitation requires an active network attacker to inject a premature response during the authentication handshake.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate enforce strict mutual authentication and cryptographic verification of both endpoints before transmitting sensitive data. Implement robust TLS/SSL configurations with explicit certificate pinning or strict CA validation to prevent Man-in-the-Middle (MITM) attackers from intercepting, prematurely concluding, or manipulating the handshake.