CVE-2026-111720
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AI Threat Summary
CVE-2026-111720 is a moderate vulnerability with a CVSS score of 5.3 affecting the target software. Authentication can be bypassed allowing unauthenticated access. Threat hunters should monitor for exploit attempts and apply vendor patches immediately.
Description
fish-island-backend through commit 7c61b78 contains an unauthenticated server-side request forgery vulnerability that allows remote attackers to make the server fetch attacker-supplied URLs via the url parameter of GET /api/web/parse. Attackers can target internal hosts, loopback services or cloud metadata endpoints through redirect-following OkHttp requests and read back page titles, meta descriptions and favicons.
Attack Chain
Attacker identifies authentication endpoint and tests for bypass conditions
Attacker exploits CVE-2026-111720 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-2026-111720 |
| CVSS Score | 5.3 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
| Published | 2026-10-16 |
| Exploited | No |
| CISA KEV | No |
| PoC | Not public |
References
- https://github.com/lhccong/fish-island-backend/blob/7c61b786…
- https://github.com/lhccong/fish-island-backend/blob/7c61b786…
- https://github.com/lhccong/fish-island-backend/blob/7c61b786…
- https://hackmd.io/@hieuPenguinnn/fish-island-web-parse-unaut…
- https://www.vulncheck.com/advisories/fish-island-backend-thr…