CVE-2026-54092: File Browser Password Validation Denial-of-Service

Technical summary

CVE-2026-54092 affects File Browser's authentication mechanism, which fails to enforce reasonable constraints on password input length. The vulnerability stems from unchecked password maximums in the login API endpoint. When a maliciously crafted request with an excessively large password payload is submitted, the application attempts to process the string without bounds-checking, triggering resource exhaustion. This maps to CWE-1284 (Improper Validation of Specified Quantity in Input) and CWE-400 (Uncontrolled Resource Consumption), both indicative of insufficient input validation and lack of resource limits. The attack requires authentication credentials but no special privileges or user interaction.

Business impact

The primary business impact is service availability. Deployments of File Browser prior to 2.63.6 are vulnerable to denial-of-service attacks from authenticated users or compromised accounts. In containerized infrastructures, exploitation can degrade or disable the entire container, potentially affecting dependent services and requiring manual intervention to restore. Organizations relying on File Browser for critical file management workflows may experience unplanned downtime. The blast radius extends beyond the vulnerable application itself—the Docker daemon errors observed during testing suggest the attack can destabilize the host platform, affecting other containerized workloads.

Affected systems

File Browser versions before 2.63.6 are affected. The vulnerability requires an authenticated session, so it is exploitable only by users with valid credentials or by threat actors who have compromised an account. Containerized deployments are at higher risk due to resource constraints and the potential for the vulnerability to propagate host-level effects.

Exploitability

Exploitability is moderate. The attack requires valid authentication credentials (PR:L in the CVSS vector), but the actual exploit is trivial—a single HTTP request to the login endpoint with a large password string triggers the vulnerability. No special tools, zero-day knowledge, or complex exploitation logic is needed. The barrier to exploitation is credential possession, not technical sophistication. Any authenticated user, whether legitimate or an account compromised through phishing or credential theft, can trigger denial of service.

Remediation

Upgrade File Browser to version 2.63.6 or later, which includes input validation fixes for password length. Organizations unable to upgrade immediately should implement network-level mitigations: restrict login API access to trusted IP ranges, enforce rate limiting on authentication endpoints, and monitor for unusual resource consumption patterns on File Browser containers. Review user access logs to identify any suspicious login attempts with unusually large payloads.

Patch guidance

Apply File Browser version 2.63.6 or later. Verify the patch by checking the application version string in the UI or via API. Test the update in a non-production environment first, particularly if File Browser is integrated with authentication systems or dependent services. Rolling updates in containerized environments are recommended to minimize downtime.

Detection guidance

Monitor File Browser login API logs for HTTP requests with unusually large password fields—specifically, payloads significantly exceeding typical password lengths (e.g., >1 MB). Observe container and host resource metrics (CPU, memory) for unexplained spikes correlated with authentication events. In Docker environments, check daemon logs for HTTP 500 errors or resource allocation failures when File Browser containers are running. Implement alerting on authentication endpoint latency; a sudden spike may indicate resource exhaustion in progress.

Why prioritize this

Although the CVSS score of 6.5 (MEDIUM) reflects the authentication requirement, the practical impact on availability justifies elevated prioritization for containerized deployments. The vulnerability can crash entire containers and disrupt the Docker daemon, affecting multiple workloads. Organizations running File Browser in production environments, especially in multi-tenant or mission-critical scenarios, should prioritize patching within their standard update cycle. The ease of exploitation once authenticated is noteworthy.

Risk score, explained

CVSS 6.5 (MEDIUM) reflects high availability impact (AV:N—network accessible, AC:L—low complexity, PR:L—low privilege required, A:H—availability highly impacted) but is constrained by the authentication prerequisite. The score appropriately captures that unauthenticated attackers cannot exploit the flaw. However, given the severity of the impact—potential container crashes and host-level disruptions in containerized environments—organizations should not dismiss this as a purely low-risk issue. The practical exploitability and blast radius warrant a risk assessment that accounts for your specific deployment model.

Frequently asked questions