CVE-2026-123204
Received Received - Intake

Server-Side Request Forgery in Posta Before v0.18.0

Publication date: 2026-11-05

Last updated on: 2026-11-05

Assigner: VulnCheck

Description
Posta before v0.18.0 contains a server-side request forgery vulnerability that allows authenticated users with edit rights to make the backend send POST requests to internal destinations by creating webhooks with arbitrary URLs. Attackers can target loopback, private-network or cloud metadata addresses and read delivery status codes and error strings to probe internal hosts and ports.

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Meta Information

Published
2026-11-05
Last Modified
2026-11-05
Generated
2026-11-06
AI Q&A
2026-11-05
EPSS Evaluated
N/A
NVD
CVE-2026-123204
EUVD
EUVD-2026-117649

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
goposta posta 0

Helpful Resources

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.

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Executive Summary

This is a Server-Side Request Forgery (SSRF) vulnerability in Posta before v0.18.0. Authenticated users with edit rights can create webhooks with arbitrary URLs, tricking the backend into sending POST requests to internal destinations like loopback addresses or private networks. Attackers can probe internal hosts and ports by reading delivery status codes and error messages.

Detection Guidance

To detect this SSRF vulnerability in Posta, check for webhook URLs pointing to internal or loopback addresses (e.g., 127.0.0.1, 192.168.x.x, 10.x.x.x). Review webhook delivery logs for failed POST requests to unexpected destinations. Use network monitoring tools to inspect outbound HTTP requests from the Posta server.

Impact Analysis

An attacker could scan your internal network, identify running services, and potentially exploit trust relationships to access sensitive systems. They might also exfiltrate data by sending it to unauthorized endpoints or pivot into trusted internal services if they rely on Posta's network position.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating GDPR's data protection principles or HIPAA's security requirements for protected health information. Organizations may face compliance violations if internal systems are compromised through this flaw.

Mitigation Strategies

Upgrade Posta to version 0.18.0 or later. Disable private network access for webhooks by setting POSTA_WEBHOOK_ALLOW_PRIVATE_NETWORKS=false. Restrict allowed networks using POSTA_WEBHOOK_ALLOWED_NETWORKS. Review and remove any existing webhooks with internal URLs.

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