Sender spoofing via Unicode thin-space display mismatch
Published Nov 5, 2025 · Updated Nov 5, 2025
Improper input validation in MDaemon Mail Server 23.5.2 allows remote authenticated users to spoof displayed email senders. During SMTP DATA processing, the server validates the address in angle brackets while clients display preceding text extended with invisible Unicode thin spaces. Reachability requires an SMTP sender able to submit a crafted message; the supplier disputes that the behavior constitutes a server flaw and attributes the display deception to clients.
Summary
What happened
Improper input validation in MDaemon Mail Server 23.5.2 allows remote authenticated users to spoof displayed email senders. During SMTP DATA processing, the server validates the address in angle brackets while clients display preceding text extended with invisible Unicode thin spaces. Reachability requires an SMTP sender able to submit a crafted message; the supplier disputes that the behavior constitutes a server flaw and attributes the display deception to clients.
The record
- CVE
- CVE-2025-61084
- Published
- Nov 5, 2025
- Updated
- Nov 5, 2025
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-116, CWE-20, T1036
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Nov 5, 2025CVE publishedPublication date reported by the CVE source.
- Nov 5, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- SMTP From header thin-space proof of conceptproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo