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engram: HTTP server CORS wildcard + auth-off-by-default enables CSRF graph exfiltration and persistent indirect prompt injection

High severity GitHub Reviewed Published Apr 18, 2026 in NickCirv/engram • Updated Apr 23, 2026

Package

npm engramx (npm)

Affected versions

< 2.0.2

Patched versions

2.0.2

Description

Summary

The local HTTP server started by engram server (binding 127.0.0.1:7337 by default) was exposed to any browser origin with no authentication unless ENGRAM_API_TOKEN was explicitly set. Combined with Access-Control-Allow-Origin: * on every response and a body parser that did not require Content-Type: application/json, this allowed a malicious web page the developer visited to:

  1. Exfiltrate the local knowledge graph via GET /query and GET /stats (function names, file layout, recorded decisions/mistakes).
  2. Inject persistent prompt-injection payloads via POST /learn, which wrote mistake/decision nodes that were later surfaced as system-reminders to the user's AI coding agent on every future session and file edit.

Severity: High — confidentiality + persistent indirect prompt injection against the user's coding agent.

Affected versions

engramx >= 1.0.0, < 2.0.2 — any version that shipped the HTTP server.

Patched in

engramx@2.0.2

Workarounds (if you cannot upgrade)

  • Do not run engram server or engram ui.
  • If developers must, set ENGRAM_API_TOKEN to a long random value and terminate the server before browsing the web.

Remediation (applied in 2.0.2)

  1. Fail-closed auth on every non-public route — Bearer header or HttpOnly cookie, constant-time comparison, 256-bit auto-generated token at ~/.engram/http-server.token (0600).
  2. Wildcard CORS removed entirely; default is no CORS headers. Opt-in allowlist via ENGRAM_ALLOWED_ORIGINS.
  3. Host + Origin validation — rejects DNS rebinding and Host spoofing.
  4. Content-Type: application/json enforced on mutations — blocks the text/plain CSRF vector.
  5. /ui?token= bootstrap with Sec-Fetch-Site gate — prevents cross-origin oracle probing.

Credit

Discovered and responsibly disclosed by @gabiudrescu in engram issue #7.

References

@NickCirv NickCirv published to NickCirv/engram Apr 18, 2026
Published to the GitHub Advisory Database Apr 22, 2026
Reviewed Apr 22, 2026
Last updated Apr 23, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction Passive
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability None
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

EPSS score

Weaknesses

Missing Authentication for Critical Function

The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. Learn more on MITRE.

Cross-Site Request Forgery (CSRF)

The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor. Learn more on MITRE.

Permissive Cross-domain Security Policy with Untrusted Domains

The product uses a web-client protection mechanism such as a Content Security Policy (CSP) or cross-domain policy file, but the policy includes untrusted domains with which the web client is allowed to communicate. Learn more on MITRE.

Initialization of a Resource with an Insecure Default

The product initializes or sets a resource with a default that is intended to be changed by the administrator, but the default is not secure. Learn more on MITRE.

CVE ID

No known CVE

GHSA ID

GHSA-2r2p-4cgf-hv7h

Source code

Credits

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