CVE-2026-90506: WARP-Clash-API Race Condition Vulnerability

CVE-2026-90506 Overview

CVE-2026-90506 is a race condition vulnerability [CWE-362] in the vvbbnn00 WARP-Clash-API project, affecting versions up to commit c7bf2360073959861219b422e51ae86411051b46. The flaw resides in an unknown function within the Save Account Job component. Attackers can trigger the race condition remotely, though exploitation requires high attack complexity and is rated difficult. The project follows a rolling release model, so no specific fixed version is published. The maintainer no longer supports this product and did not respond to disclosure attempts. A public exploit has been disclosed, increasing the risk of opportunistic exploitation attempts.

Critical Impact
Successful exploitation of the race condition in the Save Account Job can lead to limited compromise of confidentiality, integrity, and availability of account data handled by the API.

Affected Products

vvbbnn00 WARP-Clash-API up to commit c7bf2360073959861219b422e51ae86411051b46
Rolling release builds prior to any community fork patch
Deployments of the unsupported upstream project

Discovery Timeline

2026-09-13 - CVE CVE-2026-90506 published to NVD
2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-90506

Vulnerability Analysis

The vulnerability is a race condition [CWE-362] in the Save Account Job component of WARP-Clash-API. The Save Account Job runs asynchronously and manipulates shared account state without adequate synchronization. When multiple requests or job executions overlap, the ordering of read and write operations becomes non-deterministic. This creates a window where account records can be read, modified, or persisted in an inconsistent state. The exploit has been publicly disclosed, but the attack requires precise timing, which raises the practical bar for exploitation. Because the project is no longer supported, no official upstream patch will be delivered.

Root Cause

The root cause is missing atomicity around the Save Account Job's read-modify-write sequence on shared account state. Concurrent execution paths access the same resource without locking, mutexes, or transactional guarantees, producing a classic time-of-check to time-of-use exposure.

Attack Vector

The attack is network-reachable and requires low privileges but high attack complexity. An authenticated user with API access must issue concurrent requests that target the Save Account Job window to influence the outcome. Reliable exploitation depends on timing, load, and scheduler behavior, which is why the exploitability is rated difficult.

No verified proof-of-concept code is available in the enriched data. Refer to the VulDB CVE-2026-90506 entry and the public GitHub Gist for the disclosed technical details.

Detection Methods for CVE-2026-90506

Indicators of Compromise

Duplicate or inconsistent account records created within the same short time window in WARP-Clash-API data stores.
Bursts of concurrent API requests from a single authenticated identity targeting account save endpoints.
Application logs showing overlapping Save Account Job invocations for the same account identifier.

Detection Strategies

Instrument the Save Account Job with structured logging that records job start, end, and target account IDs to expose overlapping executions.
Correlate web server access logs with job execution logs to identify request patterns designed to trigger concurrent saves.
Alert on statistical anomalies in request rate to account-related endpoints from a single API key or session.

Monitoring Recommendations

Continuously monitor API traffic volume and concurrency per authenticated principal against baseline behavior.
Track database write conflicts, constraint violations, and rollback rates on account tables.
Forward application and web tier telemetry into a centralized analytics platform for cross-source correlation.

How to Mitigate CVE-2026-90506

Immediate Actions Required

Inventory all deployments of vvbbnn00 WARP-Clash-API and identify instances running commit c7bf2360073959861219b422e51ae86411051b46 or earlier rolling builds.
Restrict network exposure of the API to trusted networks or place it behind an authenticated reverse proxy with rate limiting.
Disable or gate the Save Account Job path where operationally feasible until concurrency controls are added.

Patch Information

The upstream maintainer did not respond to disclosure and the product is no longer supported, so no official patch is available. Operators should migrate to a supported alternative, fork the project and add explicit locking around the Save Account Job, or apply community patches referenced in the VulDB advisory.

Workarounds

Enforce per-account serialization of Save Account Job execution using an application-level mutex or distributed lock.
Apply strict rate limiting per authenticated identity on account write endpoints to shrink the exploitable timing window.
Add database-level unique constraints and optimistic concurrency checks to reject conflicting writes.
Retire the deployment entirely and replace it with a maintained alternative given the end-of-support status.

bash

# Configuration example: rate limit account-write endpoints at the reverse proxy
# nginx snippet
limit_req_zone $http_authorization zone=acctwrite:10m rate=2r/s;

location /api/account/save {
    limit_req zone=acctwrite burst=3 nodelay;
    proxy_pass http://warp_clash_api_upstream;
}