MDaemon Mail Server 23.5.2 validates SPF, DKIM, and DMARC using the email enclosed in angle brackets (<>) in the From: header of SMTP DATA.

published 2025-11-05 12 mo ago modified 2026-11-05 4 d ago also EUVD-2025-37764

cvss: 7.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits: 0; none known

MDaemon Mail Server 23.5.2 validates SPF, DKIM, and DMARC using the email enclosed in angle brackets (<>) in the From: header of SMTP DATA. An attacker can craft a From: header with multiple invisible Unicode thin spaces to display a spoofed sender while passing validation, allowing email spoofing even when anti-spoofing protections are in place. NOTE: this is disputed by the Supplier because UI spoofing occurs in a client, not in a server such as MDaemon's product or any other server implementation. Also, if a client without its own spoofing protection must be used, the Header Screening feature in MDaemon's product can be employed to mitigate the client-side vulnerability.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 12 mo ago (2025-11-05)

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	7.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
CNA	3.1	7.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

Classification

Weakness

CWE-116 Improper Encoding or Escaping of Output
CWE-20 Improper Input Validation

References

github.com /x00nullbit/CVE-References/blob/main/CVE-2025-61084/README.md

Sources

CVE List CVE-2025-61084
NVD CVE-2025-61084

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary