CVE-2026-71272
Received Received - Intake

Memos Webhook SSRF via DNS Rebind Attack

Publication date: 2026-08-05

Last updated on: 2026-08-05

Assigner: 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c

Description
Memos' webhook dispatch function safeDialContext() (internal/webhook/webhook.go) resolves the target hostname via net.DefaultResolver.LookupHost() and validates the resulting IPs against reserved ranges, but then dials net.JoinHostPort(host, port) using the original hostname rather than the already-validated IP address. Because net.Dialer.DialContext() performs its own independent DNS resolution, an attacker controlling DNS for the webhook's hostname (e.g. via a short TTL) can return a public, allowed IP during validation and a different, internal IP at dial time — a classic time-of-check/time-of-use DNS-rebinding bypass of the SSRF protection.

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Meta Information

Published
2026-08-05
Last Modified
2026-08-05
Generated
2026-08-05
AI Q&A
2026-08-05
EPSS Evaluated
N/A
NVD
CVE-2026-71272
EUVD
EUVD-2026-53357

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
usememos memos *

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.

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Executive Summary

This vulnerability is a Server-Side Request Forgery (SSRF) bypass via DNS rebinding. The webhook function validates a hostname's IP against reserved ranges but then uses the original hostname for the actual connection. An attacker controlling DNS can return different IPs during validation and connection, bypassing SSRF protections.

Detection Guidance

To detect this SSRF vulnerability in Memos, inspect the webhook.go file for improper hostname resolution. Check if the code validates IPs but then dials using the original hostname, allowing DNS rebinding. Review DNS logs for unexpected IP changes during webhook calls.

Impact Analysis

An attacker could exploit this to make the server send requests to internal systems or unauthorized external addresses, potentially accessing sensitive data, interacting with internal services, or exfiltrating information. This could lead to data breaches or unauthorized actions on behalf of the server.

Compliance Impact

This vulnerability could lead to unauthorized data access or exfiltration, violating GDPR's data protection principles or HIPAA's requirements for safeguarding protected health information. Compliance may be compromised if the vulnerability results in data breaches or unauthorized disclosures.

Mitigation Strategies

Update Memos to the latest version where the webhook.go file has been patched to use the validated IP address instead of the original hostname during dialing. This prevents DNS rebinding attacks by ensuring consistent IP resolution.

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