CVE-2026-56708
Received Received - Intake

Server-Side Request Forgery in Grav API Plugin via DNS Rebinding

Publication date: 2026-08-25

Last updated on: 2026-08-25

Assigner: VulnCheck

Description
Grav API plugin before 1.0.16 contains a server-side request forgery vulnerability in webhook delivery that allows attackers to bypass hostname validation by DNS rebinding. Attackers controlling authoritative DNS for a configured webhook hostname can answer validation lookups with public addresses and delivery lookups with private addresses to reach internal network resources.

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Meta Information

Published
2026-08-25
Last Modified
2026-08-25
Generated
2026-08-25
AI Q&A
2026-08-25
EPSS Evaluated
N/A
NVD
CVE-2026-56708
EUVD
EUVD-2026-65206

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
grav api_plugin to 1.0.16 (exc)
getgrav grav_api_plugin to 1.0.16 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-367 The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

Attack-Flow Graph

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Executive Summary

This is a Server-Side Request Forgery (SSRF) vulnerability in the Grav API plugin before version 1.0.16. It occurs due to a Time-of-check Time-of-use (TOCTOU) race condition where attackers exploit DNS rebinding to bypass hostname validation. Attackers controlling the DNS for a webhook hostname can respond with public IPs during validation but switch to private IPs during delivery, allowing access to internal network resources.

Detection Guidance

To detect this vulnerability, check if your Grav API plugin version is below 1.0.16. Use commands like 'composer show grav/api-plugin' or inspect the plugin directory for version files. Monitor DNS logs for unusual hostname resolutions during webhook deliveries.

Impact Analysis

An attacker could exploit this to make unauthorized requests to internal systems within your network using the Grav API plugin. This could lead to data exfiltration, internal service probing, or further attacks if internal services are compromised. The impact is limited by the fact that administrative access is already required to configure webhooks.

Compliance Impact

This vulnerability could lead to unauthorized access to internal systems, potentially violating data protection requirements under GDPR or HIPAA if sensitive data is exposed. Organizations using affected versions may face compliance risks due to insufficient network access controls.

Mitigation Strategies

Immediately update the Grav API plugin to version 1.0.16 or later. If updating is not possible, restrict outbound network access for the Grav application and disable webhook functionality until patched.

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