Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessReach public /api/web/parse endpoint
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DeliverySupply attacker-controlled url parameter
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ExploitServer-side OkHttp fetches internal/metadata URL
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ExecutionFollow redirects to restricted hosts
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PersistRead back title/meta/favicon content
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ImpactHarvest internal recon or cloud metadata
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V4 - API and Web Service URL allowlisting, SSRF prevention
MITRE ATT&CK
2 techniques across 2 tactics: Initial Access, Credential Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | No special conditions beyond network reachability - the GET /api/web/parse endpoint is exposed without authentication (PR:N) and the CorsConfig reference suggests broad cross-origin exposure, so default deployments reachable from the attacker's network are vulnerable. Exploitation specifically requires that the server can route to the targeted internal/loopback/metadata address; impact is LIMITED to data reflected through the parser (page title, meta description, favicon), so blind SSRF against services that return none of these yields little direct read-back. Real-world severity escalates only where the deployment runs in a cloud environment exposing an unauthenticated metadata endpoint (e.g., 169.254.169.254) or hosts internal HTTP services that leak sensitive titles/metadata. |
| Impact | This is a genuine but modest-severity SSRF (CWE-918) whose signals are internally consistent rather than conflicting. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N) confirms network-reachable, low-complexity, unauthenticated exploitation with no user interaction, matching the description of an open GET /api/web/parse endpoint. However, the impact metrics (VC:L/VI:N/VA:N, no subsequent-system impact) cap the real-world severity: the attacker only reads back page titles, meta descriptions, and favicons, so this is an information-exposure / internal-reconnaissance primitive, not a path to code execution or full data theft. There is no CISA KEV listing and no EPSS score was provided, and no public exploit code is referenced (only a HackMD technical write-up and a VulnCheck advisory), so active exploitation should not be assumed. The practical priority is driven less by the limited data returned and more by the blast radius: unauthenticated SSRF that can reach cloud metadata endpoints (e.g., 169.254.169.254) can escalate to credential theft depending on the hosting environment, which is why the 6.9 base score likely understates environment-specific risk. Key missing data: no EPSS probability and no vendor patch/fixed-commit are available to confirm remediation status. |
| Exploit ScenarioDerived | A remote, unauthenticated attacker sends a crafted GET request to /api/web/parse with a url parameter pointing at an internal service or cloud metadata endpoint. Because the server uses redirect-following OkHttp requests, the attacker can pivot to loopback or internal hosts and read back the fetched page's title, meta description, and favicon, enabling internal network reconnaissance or metadata exposure. No public exploit code is identified, though a detailed technical write-up (HackMD) and VulnCheck advisory describe the flaw, and the low attack complexity (AC:L) makes manual exploitation trivial. |
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Alert meAnalysisAIv1 – Oct 16, 2026
Server-side request forgery in fish-island-backend through commit 7c61b78 allows unauthenticated remote attackers to make the server fetch attacker-supplied URLs via the url parameter of GET /api/web/parse, potentially reaching internal hosts, loopback services, and cloud metadata endpoints through redirect-following OkHttp requests. Successful exploitation can disclose limited internal data reflected by the parser, such as page titles, meta descriptions, and favicons, so the practical impact is constrained to what the targeted service returns in those fields. No public exploit code or CISA KEV entry is identified in the provided data, and the assessed CVSS:3.1 vector is AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
RemediationAI
No vendor-released patch identified at time of analysis; fix by updating to a commit after 7c61b78 if upstream provides one, or apply these compensating controls. Require authentication and authorization on GET /api/web/parse and validate that the url parameter is an allowlisted scheme and host, rejecting redirects to private, loopback, link-local, and metadata addresses such as 169.254.169.254 and their IPv6 equivalents; this may break legitimate use against URLs that redirect. Configure the OkHttp client to disable redirect following (followRedirects(false)) and to resolve and pin DNS before connecting to prevent DNS rebinding, with the trade-off that some legitimate sites requiring redirects will no longer be parsed correctly. Enforce outbound network egress filtering so the application server cannot reach internal management networks or cloud metadata services, which may require changes to firewall rules and could affect other outbound integrations. If the service runs in AWS, require IMDSv2 with token-based access and set hop limit to 1 to mitigate metadata credential exposure, understanding that IMDSv2 support is mandatory and may affect legacy tooling. Review the CorsConfig.java configuration to restrict cross-origin access to trusted origins as an additional defense-in-depth measure. Advisory references: https://www.vulncheck.com/advisories/fish-island-backend-through-commit-7c61b78-ssrf-via-api-web-parse and https://hackmd.io/@hieuPenguinnn/fish-island-web-parse-unauth-ssrf.
Affected VersionsENISA
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Technical ContextAI · show details
The vulnerability is CWE-918 (Server-Side Request Forgery) in the Java-based fish-island-backend application. The controller at WebParserController.java lines 13-25 exposes GET /api/web/parse to unauthenticated callers and passes a user-controlled url parameter into WebParserServiceImpl.java lines 28-45, which uses OkHttp to retrieve the remote page. OkHttp follows HTTP redirects by default, so an attacker can supply a URL that redirects to a private address, loopback service, or link-local metadata endpoint (for example 169.254.169.254); the parser then reflects page title, meta description, and favicon data back to the attacker. The CPE cpe:2.3:a:lhccong:fish-island-backend:*:*:*:*:*:*:*:* indicates all versions through the referenced commit, and the CorsConfig.java line 33 reference in the advisory notes broad cross-origin configuration that may also allow browser-driven exploitation, though the primary vector is direct network access. No authentication requirement is indicated by the CVSS vector PR:N, consistent with the unauthenticated endpoint.
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Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Unauthenticated network endpoint with low complexity (AV:N/AC:L/PR:N/UI:N); only limited internal data is read back, so C:L and I:N/A:N, scope unchanged as impact stays within the app.
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
DescriptionCVE.org
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.
Threat Intelligence Overview
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Server-Side Request Forgery exploits applications that fetch remote resources based on user-supplied URLs.
EUVD-2026-103012
GHSA-mc35-74mg-3v34
NVD
CVE.org
Exploit-DB