usememos Memos up to 0.29.1 Webhook URL Validation validate.go isReservedIP redirect

Summaryinfo

A vulnerability was found in usememos Memos up to 0.29.1. It has been rated as problematic. This impacts the function isReservedIP of the file internal/webhook/validate.go of the component Webhook URL Validation. This manipulation causes redirect. This vulnerability is tracked as CVE-2026-71271. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in usememos Memos up to 0.29.1. It has been declared as problematic. Affected by this vulnerability is the function isReservedIP of the file internal/webhook/validate.go of the component Webhook URL Validation. The manipulation with an unknown input leads to a redirect vulnerability. The CWE definition for the vulnerability is CWE-601. A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks. As an impact it is known to affect integrity. The summary by CVE is:

Memos' webhook URL validation, isReservedIP() (internal/webhook/validate.go), checks a candidate IP against a reservedCIDRs list that omits 0.0.0.0/8 and never calls ip.IsUnspecified() — unlike the correctly implemented sibling function isInternalIP() in internal/httpgetter/html_meta.go, which does. Because Linux redirects connections to 0.0.0.0 to loopback (127.0.0.1), an attacker registering a webhook URL of http://0.0.0.0:PORT/ bypasses the reserved-IP check and causes the Memos server to make outbound HTTP requests to its own loopback interface, exposing internal-only services.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-71271 since 08/05/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/05/2026). MITRE ATT&CK project uses the attack technique T1204.001 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• usememos

Name

• Memos

Version

• 0.29.0
• 0.29.1

License

• open-source

CPE 2.3info

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CPE 2.2info

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