CVE-2026-21755: HCL Hive Auth Bypass Vulnerability

CVE-2026-21755 Overview

CVE-2026-21755 is a missing rate limit vulnerability in HCL Hive. The flaw allows unauthenticated attackers to submit unlimited authentication requests over the network. This creates opportunities for brute-force password guessing, credential stuffing using stolen credential databases, and denial-of-service conditions against the authentication service. The weakness is classified as Improper Restriction of Excessive Authentication Attempts [CWE-307]. HCL Software published a knowledge base article documenting the issue and remediation guidance.

Critical Impact
Unauthenticated network attackers can execute brute-force or credential stuffing attacks against HCL Hive authentication endpoints, potentially leading to unauthorized account access or service disruption.

Affected Products

HCL Hive (specific affected versions listed in the HCL Software knowledge base)

Discovery Timeline

2026-08-24 - CVE-2026-21755 published to NVD
2026-08-24 - Last updated in NVD database

Technical Details for CVE-2026-21755

Vulnerability Analysis

HCL Hive fails to enforce a rate limit on authentication-related requests. Attackers can send high-volume requests to login or credential-validation endpoints without triggering lockout, throttling, or CAPTCHA controls. This enables automated credential guessing at machine speed.

Two attack outcomes are possible. First, attackers achieve unauthorized access when a guessed or reused credential succeeds against a valid account. Second, high request volume exhausts backend authentication resources, degrading availability for legitimate users. The CVSS metrics reflect low integrity impact with network reachability and no privileges required.

The underlying weakness maps to CWE-307: Improper Restriction of Excessive Authentication Attempts. This class of flaw is common in web applications and APIs where developers rely solely on password strength rather than pairing it with attempt-based controls.

Root Cause

The application does not track or limit failed authentication attempts per account, per source IP, or per session. Without such counters, backoff timers, or lockout thresholds, the authentication endpoint accepts unbounded submissions. Missing rate-limit middleware or reverse-proxy protection is the typical root cause for this vulnerability class.

Attack Vector

Exploitation requires network access to the HCL Hive authentication interface. An attacker scripts a client to iterate through candidate username and password pairs sourced from public credential dumps or common password lists. Because no throttling is applied, the attacker can sustain high request rates limited only by network bandwidth and server capacity. Refer to the HCL Software Knowledge Base Article for vendor technical details.

Detection Methods for CVE-2026-21755

Indicators of Compromise

High volume of failed authentication events originating from a single source IP or narrow IP range within a short window.
Sequential authentication attempts across many usernames from the same source, characteristic of credential stuffing.
Successful logins immediately preceded by dozens or hundreds of failed attempts against the same account.
Sudden spikes in HTTP request rates to /login or authentication API paths.

Detection Strategies

Correlate authentication logs to identify brute-force patterns: many failures per source, many usernames per source, or many sources per username.
Alert on impossible-travel or geo-anomalous successful logins that follow bursts of failures.
Deploy Web Application Firewall (WAF) rules that count authentication requests per client and flag threshold breaches.

Monitoring Recommendations

Ingest HCL Hive authentication logs into a centralized SIEM for real-time correlation.
Track baseline authentication request rates and alert on statistical deviations.
Monitor account lockout, password reset, and MFA challenge volumes as secondary signals of credential attacks.

How to Mitigate CVE-2026-21755

Immediate Actions Required

Apply the vendor fix documented in the HCL Software Knowledge Base Article.
Force password resets for accounts showing evidence of brute-force targeting or successful anomalous logins.
Enable multi-factor authentication (MFA) for all HCL Hive accounts to blunt credential stuffing success.

Patch Information

HCL Software has published remediation details in knowledge base article KB0131731. Administrators should consult the vendor advisory to identify the fixed release and upgrade path for their deployment. Verify version parity across all HCL Hive instances after patching.

Workarounds

Place HCL Hive behind a reverse proxy or WAF that enforces per-IP and per-account authentication rate limits.
Implement account lockout thresholds and progressive backoff at the network edge until the patch is applied.
Restrict access to authentication endpoints via IP allowlists or VPN where the deployment model permits.
Deploy CAPTCHA or bot-mitigation controls in front of the login interface to disrupt automated attacks.

bash

# Example nginx rate-limit configuration for authentication endpoints
http {
    limit_req_zone $binary_remote_addr zone=auth_zone:10m rate=5r/m;

    server {
        location /login {
            limit_req zone=auth_zone burst=5 nodelay;
            proxy_pass http://hcl_hive_backend;
        }
    }
}