Summary
ApostropheCMS: Host header controls server-side image fetch origin in @apostrophecms/ai-helper, enabling authenticated SSRF
Impact
An attacker who holds a low-privileged editor account (the capability required to generate an AI image, which inserts a base64 record without a stored url and returns its identifier) can coerce the server into issuing outbound GET requests to an origin of their choosing by supplying a crafted Host header on the accept request. This yields SSRF: probing internal hosts and ports that are not reachable from the attacker's network position, and limited semi-blind exfiltration where an image-parseable response at the fixed path becomes a viewable attachment. The request path is fixed to /uploads/ai-helper-images/<id>.png, so only the origin (host, port, and http scheme) is attacker-controlled; arbitrary-path retrieval such as cloud metadata traversal is not reachable through this primitive. No integrity or availability primitive was demonstrated. Exploitation requires the default deployment where no global base URL is configured and local file storage is in use, together with a configured provider that returns base64 image data.
Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.
CVE-2026-113671 has a CVSS score of 4.3 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.0.0-beta.13); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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See it in your environmentNew to Kodem? Get a demo →Remediation advice
Do not treat req.baseUrl as a trusted origin for a server-side fetch. Enforce the same authorization on the accept route that the generate route applies, and add an ownership or scope check so a record can only be accepted by a user permitted to act on it. Independently, constrain the fetch target: resolve the storage-relative path against a server-configured, trusted base (for example the configured storage base URL) rather than the request-derived req.baseUrl, and reject or allowlist any resulting origin before calling fetch. Ensure the remediation covers both the base64 (no stored url) representation and the stored-url representation, and any other caller that reaches aiHelperImageUrl or aiHelperFetchImage. As an interim mitigation without a code change, configure a global base URL so the resolved origin is fixed, and place egress controls on the server so outbound requests cannot reach sensitive internal hosts or metadata endpoints.
Reported by zx (GitHub: @manus-pi).
Frequently Asked Questions
- What is CVE-2026-113671? CVE-2026-113671 is a medium-severity server-side request forgery (SSRF) vulnerability in @apostrophecms/ai-helper (npm), affecting versions >= 1.0.0-beta.10, < 1.0.0-beta.13. It is fixed in 1.0.0-beta.13. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
- How severe is CVE-2026-113671? CVE-2026-113671 has a CVSS score of 4.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of @apostrophecms/ai-helper are affected by CVE-2026-113671? @apostrophecms/ai-helper (npm) versions >= 1.0.0-beta.10, < 1.0.0-beta.13 is affected.
- Is there a fix for CVE-2026-113671? Yes. CVE-2026-113671 is fixed in 1.0.0-beta.13. Upgrade to this version or later.
- Is CVE-2026-113671 exploitable, and should I be worried? Whether CVE-2026-113671 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-113671 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-113671? Upgrade
@apostrophecms/ai-helperto 1.0.0-beta.13 or later.