CVE-2026-76239
Received Received - Intake

SSRF via Unvalidated Webhook Delivery Address in Stigmem

Publication date: 2026-08-19

Last updated on: 2026-08-19

Assigner: VulnCheck

Description
Stigmem before 0.9.0a11 fails to validate the delivery_address parameter when creating webhook subscriptions, allowing authenticated users to specify internal loopback and private network destinations. Attackers can trigger matching fact-change events to cause the Stigmem server to issue server-side HTTP POST requests to internal services, enabling blind SSRF attacks against localhost and private network endpoints.

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Meta Information

Published
2026-08-19
Last Modified
2026-08-19
Generated
2026-08-19
AI Q&A
2026-08-19
EPSS Evaluated
N/A
NVD
CVE-2026-76239
EUVD
EUVD-2026-62403

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
stigmem stigmem to 0.9.0a11 (exc)
eidetic_labs stigmem to 0.9.0a11 (exc)
eidetic_labs stigmem_node to 0.9.0a11 (exc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-918 The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Attack-Flow Graph

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Executive Summary

CVE-2026-76239 is a Server-Side Request Forgery (SSRF) vulnerability in Stigmem versions before 0.9.0a11. It occurs because the application fails to validate the delivery_address parameter when creating webhook subscriptions. Authenticated users can specify internal loopback or private network destinations, causing the server to send HTTP POST requests to those targets when triggered by fact-change events. This enables blind SSRF attacks against localhost and private network endpoints.

Detection Guidance

To detect this vulnerability, inspect Stigmem server logs for unusual HTTP POST requests to internal or loopback addresses. Check webhook subscription configurations for delivery_address parameters pointing to 127.0.0.1, localhost, or private network ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16). Use network monitoring tools to capture outbound connections from the Stigmem server to unexpected destinations.

Impact Analysis

An attacker could exploit this to probe internal services, access localhost-only admin services, interact with private network services, or reach cloud metadata endpoints if accessible from the server. Even without response data, the attacker can infer internal reachability through delivery status, retry behavior, circuit-breaker behavior, or logs.

Compliance Impact

This SSRF vulnerability could potentially violate compliance with GDPR and HIPAA by enabling unauthorized access to internal services. GDPR requires protecting personal data and ensuring secure processing, while HIPAA mandates safeguarding protected health information. The flaw allows attackers to probe internal systems, which may expose sensitive data or systems handling regulated information.

Mitigation Strategies

Upgrade Stigmem to version 0.9.0a11 or later to apply the patch. Ensure the delivery_address parameter is validated using the existing assert_safe_url() function during both subscription creation and webhook delivery. Block loopback, private, and metadata-style addresses. Prefer HTTPS-only URLs and implement allowlists for HTTP if necessary. Re-validate destinations before delivery to prevent DNS rebinding.

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