CVE-2026-26747

critical · 9.1

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,

9.1

CVSS

0.4%

EPSS (exploit prob.)

34th

EPSS percentile

2026-02-20

Published

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Weaknesses

CWE-644

Affected products

Vendor	Product	Affected versions
monicahq	monica	4.1.2

Check a specific version with /api/v1/cve/match.

References

https://github.com/hungnqdz/cve-research/blob/main/CVE-2026-26747.md
https://github.com/monicahq/monica

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2026-26747