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HIGH · 8.5

CVE-2026-71271

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 co...

Vulnerability Description

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.

CVSS Score

8.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality
HIGH
Integrity
LOW
Availability
NONE

Related Weaknesses (CWE)

CWE-918

References

FAQ

What is CVE-2026-71271?

CVE-2026-71271 is a vulnerability with a CVSS score of 8.5 (HIGH). 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 co...

How severe is CVE-2026-71271?

CVE-2026-71271 has been rated HIGH with a CVSS base score of 8.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-71271?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.