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.

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,

EPSS: 0.004 (31.7th percentile) — read the EPSS interpretation.

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.

Affected products

Monicahq Monica — versions 4.1.2
N/a — versions n/a

Weakness classification (CWE)

CWE-644 — Improper Neutralization of HTTP Headers for Scripting Syntax

References

cve@mitre.org (Product)
cve@mitre.org (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.