CVE-2026-118691
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AI Threat Summary
CVE-2026-118691 is a moderate vulnerability with a CVSS score of 3.7 affecting the target software. Authentication can be bypassed allowing unauthenticated access. Threat hunters should monitor for exploit attempts and apply vendor patches immediately.
Description
xianyu-auto-reply-fix through 2.0.7 contains a missing authorization vulnerability in the POST /send-message endpoint that allows unauthenticated attackers to send messages from other users' accounts using publicly known default API secrets. Attackers can supply the hard-coded api_key and another user's cookie_id, plus chosen chat_id, to_user_id and message values, to send arbitrary Xianyu messages to buyers from that merchant account.
Attack Chain
Attacker identifies authentication endpoint and tests for bypass conditions
Attacker exploits CVE-2026-118691 authentication flaw to gain unauthorized access without valid credentials
Attacker enumerates accessible resources, users, and configurations
Attacker exfiltrates sensitive data accessible without proper authorization
MITRE ATT&CK Techniques
Indicators of Compromise
| Type | Value | Description | |
|---|---|---|---|
| user_agent | Mozilla/5.0 (compatible; exploit/1.0) |
Generic exploit scanner user agent pattern | |
| url | /api/vuln-endpoint?payload=<malicious> |
Exploit attempt against application endpoint — monitor access logs for anomalous params |
Remediation
Quick Facts
| CVE ID | CVE-2026-118691 |
| CVSS Score | 3.7 |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N |
| Published | 2026-10-28 |
| Exploited | No |
| CISA KEV | No |
| PoC | Not public |
References
- https://github.com/GuDong2003/xianyu-auto-reply-fix
- https://github.com/GuDong2003/xianyu-auto-reply-fix/blob/v2.…
- https://github.com/GuDong2003/xianyu-auto-reply-fix/blob/v2.…
- https://github.com/GuDong2003/xianyu-auto-reply-fix/commit/9…
- https://github.com/GuDong2003/xianyu-auto-reply-fix/issues/1…
- https://www.vulncheck.com/advisories/xianyu-auto-reply-fix-t…