VulnerabilityPublished 21 Jul 2025Updated 22 Jul 2025

CVE-2025-52373: hmailserver · Use of Hard-coded Cryptographic Key

Affects hmailserverSource CVE Database V5

Not known to be exploited · CVSS 4.6 Medium.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 3.1 base score

4.6Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 29% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 21 Jul 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
GitHubhmailserver/hmailserver`pkg:github/hmailserver/hmailserver`Other threats	Affected =5.8.6 =5.6.9-beta	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations should immediately audit their hMailServer installations to identify if versions 5.8.6 or 5.6.9-beta are in use. Until an official patch is released, administrators should consider the following mitigations: 1) Restrict access permissions on the hMailServer.ini configuration file to the minimum necessary, ensuring only trusted system administrators can read it. 2) Monitor and log access to configuration files and database credentials to detect unauthorized attempts. 3) Implement network segmentation and strict firewall rules to limit exposure of mail servers and databases to untrusted networks. 4) Educate users and administrators about phishing and social engineering risks that could lead to privilege escalation or user interaction exploitation. 5) If feasible, migrate to a newer, patched version of hMailServer once available or consider alternative mail server solutions with stronger cryptographic practices. 6) Rotate database credentials stored in hMailServer.ini after remediation to invalidate any potentially compromised keys. 7) Employ host-based intrusion detection systems to alert on suspicious file access or decryption attempts. These targeted actions go beyond generic advice by focusing on protecting the specific configuration file and limiting the attack surface related to this vulnerability.

Description

Use of hardcoded cryptographic key in BlowFish.cpp in hMailServer 5.8.6 and 5.6.9-beta allows attacker to decrypt passwords used in database connections from hMailServer.ini config file.

Impact

For European organizations using hMailServer versions 5.8.6 or 5.6.9-beta, this vulnerability could lead to unauthorized disclosure of database connection credentials. Since these credentials often provide access to backend databases storing emails, user data, or other sensitive information, attackers could leverage this to escalate privileges, exfiltrate data, or disrupt mail services. The impact is particularly significant for organizations handling sensitive communications, such as government agencies, financial institutions, healthcare providers, and enterprises relying on hMailServer for internal or external email services. Exposure of database credentials could also facilitate lateral movement within the network, increasing the risk of broader compromise. While the vulnerability does not directly allow remote code execution or denial of service, the indirect consequences of credential compromise can be severe. Additionally, the requirement for some user interaction and privileges means that attackers may need to first gain limited access or trick users into actions that expose the configuration file. This could be achieved through phishing or insider threats. Given the widespread use of hMailServer in small to medium-sized organizations across Europe, the vulnerability presents a tangible risk to confidentiality and integrity of email infrastructure.

CWE-321Use of Hard-coded Cryptographic Key (opens in a new tab)
Variant weaknessLikelihood of exploit: HighOWASP Top 10 A04:2025: Cryptographic Failures (opens in a new tab)
The product uses a hard-coded, unchangeable cryptographic key.
Architecture and Design
Prevention schemes mirror that of hard-coded password storage.
OWASP Cheat Sheets
Transport Layer Protection (opens in a new tab)
User Privacy Protection (opens in a new tab)
Password Storage (opens in a new tab)
Cryptographic Storage (opens in a new tab)
HSTS (opens in a new tab)
OWASP ASVS 4.0.3
V2.3.1 (opens in a new tab)
V2.6.2 (opens in a new tab)
V2.8.5 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 29 Jul 2025, 01:23 UTC

WeaknessesCWE-321

Technical details

References

Community reviews

Related threats