What’s Vulnerable › Vulnerabilities
CVE-2026-13163: Lack of input validation in Mailerup input parameter leads to Open Redirect
- Severity: medium (CVSS 5.3 v4.0)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.5% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-06-24 · updated 2026-10-24
- Weakness: CWE-601
Description
Open redirect vulnerability (CWE-601) in the _safe_redirect function of the click-tracking endpoint (/c/<token>/) in Mailerup <1.0.0 on all platforms allows remote unauthenticated attackers to redirect victims to arbitrary external sites and conduct phishing attacks via a crafted u query parameter, because the URL scheme is validated (blocking javascript: and data:) but the destination host is not restricted to an allowlist, and a signing.BadSignature exception is silently caught so a valid signed token is not required.
Affected products
- Mailerup: before 1.0.1 — fixed in 1.0.1
How to fix
Upgrade to a fixed version: Mailerup 1.0.1. Check the vendor advisory for mitigations.
References
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