EUVD-2026-81039
GHSA-7mqp-q79v-g27v
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessObtain page-editing account
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DeliveryInject img with prefetch-candidate class targeting internal URL
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ExploitServer prefetch renderer fetches URL without validation
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ExecutionResponse returned to attacker
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ImpactExfiltrate cloud metadata/internal service data
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 | Requires an authenticated Wiki.js account with page-editing permissions (PR:L); anonymous/unauthenticated users cannot reach the vector. Exploitation uses the Image Prefetch renderer feature: the attacker injects an img element with the prefetch-candidate class whose src points to an internal or metadata URL, and the server fetches it without protocol, host, or IP/address validation, returning the response to the attacker. No user interaction beyond the attacker's own page edit is needed, and default configurations that permit content editing and run the image-prefetch rendering pipeline are exploitable. The main limiting factor is the requirement to hold editing rights, plus the server needing network reachability to the intended internal/metadata target. |
| Impact | This is a genuine but moderate-priority issue. The vendor CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N) describes a network-reachable, low-complexity, authenticated (PR:L) SSRF with high confidentiality impact and no integrity or availability impact - a shape consistent with the CWE-918 classification and the description. The strongest escalating signal is that the SSRF is NON-blind: responses are returned to the attacker, so it directly enables reading internal services and cloud metadata endpoints (e.g., IMDS credential theft), which is why VC:H is justified. A public POC exists (geo-chen/oss writeup, referenced by VulnCheck), raising practical exploitability, but there is no CISA KEV listing and no EPSS score provided, so there is no evidence of active or widespread exploitation. The key limiter is PR:L: the attacker must already hold page-editing permissions on the wiki, narrowing the population to authenticated contributors/editors rather than the anonymous internet. Net: a real, POC-backed SSRF worth patching promptly in exposed deployments, but not a drop-everything unauthenticated critical. |
| Exploit ScenarioDerived | An attacker with a page-editing account on Wiki.js creates or edits a page containing an img element carrying the prefetch-candidate class and a src pointing at an internal target (e.g., http://169.254.169.254/latest/meta-data/ or an internal admin service). The server-side Image Prefetch renderer fetches that URL without protocol/host/address validation and returns the response content to the attacker, enabling internal reconnaissance and cloud-credential theft. A public proof-of-concept for this exact vector is available. |
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Alert meAnalysisAIv1 – Sep 16, 2026
Server-side request forgery in Wiki.js through 2.5.314 lets an authenticated user who holds page-editing permissions force the server to fetch arbitrary URLs on their behalf, including internal services and cloud instance metadata endpoints, with the fetched response returned to the attacker. The flaw sits in the Image Prefetch renderer, which resolves the src of any img element tagged with the prefetch-candidate class without validating protocol, host, or resolved address; publicly available exploit code exists, and the assessed impact is information disclosure only (high confidentiality, no integrity or availability effect). Exploitation is constrained by the need for an account with editing rights and by the server's network reachability to the intended internal or metadata target, making this a genuine but moderate-priority issue rather than a pre-auth or remote-code-execution class bug.
RemediationAI
No vendor-released patch was identified at time of analysis: the available references point to the vulnerable 2.5.314 source file and to the VulnCheck advisory (https://www.vulncheck.com/advisories/wiki-js-through-2.5.314-server-side-request-forgery-via-image-prefetch), which is accompanied by public proof-of-concept material (https://github.com/geo-chen/oss/blob/main/wiki.md), but no fixed release, commit, or PR is cited, so administrators should track the upstream project at github.com/requarks/wiki for a patched version and treat any future release note referencing the html-image-prefetch renderer as the fix indicator. Until a patch lands, the most direct mitigation is to disable the html-image-prefetch rendering module in the Wiki.js renderer configuration; the trade-off is that remote images referenced in pages will no longer be prefetched or cached server-side, which degrades offline image availability and page load performance for externally hosted images. In parallel, tighten the authorization surface by auditing who holds page-editing rights, since the vulnerability is only reachable by authenticated users with editing permissions (PR:L), and by restricting write access to trusted editors. Network-level compensating controls are also effective: apply egress firewall or Kubernetes network policy rules that block outbound traffic from the Wiki.js host to RFC1918 private ranges, loopback, link-local 169.254.0.0/16 and IPv6 equivalents, and cloud metadata endpoints, and require IMDSv2 or equivalent token-gated metadata access on the hosting platform; the trade-off here is that legitimate outbound calls (mail relays, external APIs, remote image hosts) must be explicitly allow-listed, and any missed allow-list entry will surface as a functional failure. Because the renderer reportedly performs no protocol validation, egress rules should not be limited to HTTP/HTTPS ports but should restrict all outbound schemes and destinations from the application process.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Wiki.js is a Node.js-based wiki platform whose content rendering pipeline is decomposed into modular renderers; the vulnerable component is the HTML image prefetch renderer (server/modules/rendering/html-image-prefetch/renderer.js), which scans rendered page content for img elements carrying the prefetch-candidate class and then performs a server-side fetch of the referenced URL in order to cache or inline the remote image. According to the advisory, that fetch applies no protocol, host, or IP-address validation, so the destination is fully attacker-controlled. This is a classic CWE-918 server-side request forgery: instead of the request originating from the victim's browser (where same-origin and network boundaries would apply), it originates from the Wiki.js server, which typically sits inside a trusted network segment and can therefore reach internal-only HTTP services, admin interfaces bound to localhost or private ranges, and link-local cloud metadata services such as 169.254.169.254. The reported behavior also returns the fetched response body to the attacker, converting the SSRF into a read primitive rather than a blind request-forwarding primitive, which is what drives the high confidentiality rating in the independent assessment; the absence of any protocol validation noted in the description further widens the set of reachable schemes and targets well beyond ordinary http/https image URLs.
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Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Network-reachable, low-complexity SSRF requiring an authenticated editor (PR:L); non-blind responses return sensitive internal/metadata data (C:H) with no integrity or availability impact.
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
DescriptionCVE.org
Wiki.js through 2.5.314 contains a server-side request forgery vulnerability in the Image Prefetch renderer that fetches arbitrary URLs without protocol, host, or address validation. Attackers with page editing permissions can inject img elements with the prefetch-candidate class to make the server request internal services and cloud metadata endpoints, with responses returned to the attacker.
Technical POC Analysis
Server-side request forgery (CWE-918) in Wiki.js's own application code, not in a third-party library.
Full technical POC analysis - root cause, step-by-step exploitation and patch breakdown - is part of the Pro and Business plans.
Latest POC
1 PoC candidate from github (unverified)
Sign in to open the public PoC links collected for this CVE.
Executive ViewAI
Wiki.js deployments up to and including version 2.5.314 contain a server-side request forgery flaw in the Image Prefetch renderer that allows a user with page-editing rights to make the wiki server fetch arbitrary internal or cloud metadata URLs and return the responses to them. The exposure is confidentiality-only - no data manipulation or service outage is expected - but any leaked credentials, tokens, or configuration pulled from internal endpoints or cloud instance metadata could enable a much larger follow-on compromise. Leadership should treat this as a moderate-priority remediation item driven by entitlement sprawl and network reachability rather than an urgent pre-access or code-execution emergency.
No vendor-released patch identified at time of analysis. Interim mitigations: tighten page-editing entitlements to the smallest possible user set; disable or remove the Image Prefetch renderer / prefetch-candidate functionality if configurable; block server egress to link-local and loopback ranges and cloud metadata endpoints (169.254.169.254) at the host firewall or network layer; enforce IMDSv2 or provider-equivalent metadata protections; segment the Wiki.js host away from sensitive internal services; and monitor and alert on anomalous outbound requests and metadata access attempts.
Threat Intelligence Overview
NVD
CVE.org
EPSS
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.
Authorization bypass in Wiki.js through 2.5.314 allows an authenticated user who has been granted access to at least one
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