Vulnerability in Monicahq Monica
CVE-2026-26747
A Host Header Poisoning vulnerability exists in Monica 4.1.2 due to improper handling of the HTTP Host header in app/Providers/AppServiceProvider.php, combined with the default misconfiguration where the "app.force_url" is not set and default is "false". The application generates absolute URLs (such as those used in password reset emails) using the user-supplied Host header. This allows remote attackers to poison the password reset link sent to a victim,
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.006 (45.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 45.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.006 · change: +0.002
Affected products
- Monicahq Monica — versions 4.1.2
Weakness classification (CWE)
References
- github.com/monicahq/monica (Product)
- github.com/hungnqdz/cve-research/blob/main/CVE-2026-26747.md (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-26747?
- CVE-2026-26747 is a critical-severity vulnerability in Monicahq Monica, classified under Improper Neutralization of HTTP Headers for Scripting Syntax. CVSS score: 9.1/10. Published 2026-02-20.
- How severe is CVE-2026-26747?
- Critical severity. CVSS v3 base score is 9.1 out of 10.