VulnerabilityPublished 8 Dec 2024Updated 9 Dec 2024

CVE-2024-55560: MailCleaner before 28d913e has default values of ssh_host_dsa_key, ssh_host_rsa_key, and

Source CVE Database V5

Not known to be exploited · CVSS 9.8 Critical.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

9.8Critical

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 47% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 8 Dec 2024
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 or the CVSS exploit maturity 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

AI-suggested

To mitigate CVE-2024-55560, organizations should immediately verify if their MailCleaner installations are using default SSH host keys. Administrators must regenerate SSH host keys (DSA, RSA, ED25519) to unique values immediately after installation or upgrade. This can typically be done by deleting the existing default keys and running the SSH key generation commands (e.g., ssh-keygen) on the MailCleaner server. Additionally, upgrading MailCleaner to the version including commit 28d913e or later is critical, as this update ensures default keys are not reused. Network administrators should also monitor SSH connections to MailCleaner servers for anomalies indicative of MITM attacks. Implementing strict SSH host key verification policies and using out-of-band methods to verify host keys can further reduce risk. Finally, organizations should audit their email security infrastructure regularly to detect any signs of compromise related to this vulnerability.

Description

MailCleaner before 28d913e has default values of ssh_host_dsa_key, ssh_host_rsa_key, and ssh_host_ed25519_key that persist after installation.

Impact

The impact of CVE-2024-55560 is severe for organizations relying on MailCleaner for email security. Attackers exploiting this vulnerability can impersonate the MailCleaner server, intercept or alter email traffic, and potentially gain unauthorized access to internal networks. This compromises the confidentiality and integrity of sensitive communications and can lead to further lateral movement within the network. The availability of the service may also be disrupted if attackers manipulate SSH connections or credentials. Given the critical CVSS score and the lack of required authentication, the vulnerability poses a significant risk to organizations’ email infrastructure, potentially enabling espionage, data breaches, and service outages. The threat is especially acute for enterprises, government agencies, and service providers that depend on MailCleaner for filtering and securing email traffic. Without timely mitigation, attackers could leverage this vulnerability to undermine trust in secure communications and gain footholds for broader attacks.

References

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