CVE-2026-77771 in 2FA Plugin
Summary
by MITRE • 09/10/2026
The miniOrange 2FA WordPress plugin before 6.3.1, miniOrange 2FA WordPress plugin before 19.3 does not scope its second-factor attempt limit to the account being attacked, keying it instead to an identifier the client supplies and can change at will, allowing an attacker who already knows a victim's password to make unlimited one-time-passcode guesses and defeat the second factor. A second validation endpoint applies no attempt limit at all.
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Analysis
by VulDB Data Team • 09/10/2026
The vulnerability identified in miniOrange 2FA plugins for WordPress prior to versions 6.3.1 and 19.3 represents a critical failure in authentication logic, specifically concerning rate limiting mechanisms designed to prevent brute-force attacks against second-factor credentials. The core technical flaw lies in the implementation of attempt limits for one-time passcode verification. Instead of binding these limits to specific user accounts or unique session identifiers that are difficult for an attacker to manipulate, the system keys the restriction on a client-supplied identifier. This design choice allows malicious actors who have already obtained valid victim credentials through phishing, credential stuffing, or data breaches to bypass security controls by altering this identifier at will during their attack sequence. Consequently, the intended protection against rapid guessing is rendered ineffective because each change in the supplied identifier resets the attempt counter, granting the attacker unlimited opportunities to guess the correct one-time passcode without triggering account lockouts or alerts.
This architectural weakness directly undermines the fundamental purpose of two-factor authentication, which is to add a layer of security that remains robust even if primary credentials are compromised. By allowing unrestricted guessing attempts against the second factor, the vulnerability effectively reduces multi-factor authentication to single-factor authentication in practice for targeted attacks. An attacker with knowledge of a victim's username and password can systematically iterate through possible passcode values until one is accepted, thereby gaining full unauthorized access to the user account. This scenario poses severe risks including data exfiltration, privilege escalation if the compromised account has administrative rights, and potential lateral movement within an organization’s infrastructure depending on the privileges associated with the targeted WordPress site or its connected services.
From a classification perspective, this issue aligns closely with CWE-307 Improper Restriction of Excessive Authentication Attempts, as the system fails to enforce adequate limits on repeated authentication attempts for a specific identity. Furthermore, it relates to CWE-640 Weak Password Recovery Mechanism for Forgotten Password if the passcode generation or reset logic is involved in the bypass path, though the primary issue remains the lack of proper session-based rate limiting. In terms of offensive security frameworks such as MITRE ATT&CK, this vulnerability facilitates techniques associated with Credential Access and Defense Evasion, specifically allowing attackers to bypass multi-factor authentication controls through brute-force methods that exploit implementation flaws rather than cryptographic weaknesses. The existence of a second validation endpoint that applies no attempt limit whatsoever exacerbates the severity by providing an alternative attack vector where rate limiting is entirely absent, further increasing the probability of successful compromise for determined adversaries.
Mitigation strategies must focus on correcting the fundamental logic errors in how authentication attempts are tracked and limited. Developers should ensure that all rate-limiting mechanisms are scoped to unique user identities or immutable session tokens rather than mutable client-supplied parameters like IP addresses or custom identifiers that can be spoofed or rotated easily by automated tools. Implementing strict server-side validation of these identifiers is essential, along with enforcing consistent attempt limits across all authentication endpoints within the plugin. Additionally, organizations should consider implementing adaptive authentication policies that detect anomalous behavior patterns indicative of brute-force attacks and respond with temporary account locks or CAPTCHA challenges regardless of the identifier used during login attempts. Updating to patched versions 6.3.1 and later is critical for immediate remediation, as these releases address the scoping issue by properly binding attempt limits to user accounts rather than external identifiers. Security teams should also monitor logs for unusual spikes in authentication failures associated with single users or specific IP ranges to detect ongoing exploitation attempts even after patching has been applied.