CVE-2025-52557VulnerabilityPublished 21 Jun 2025Updated 23 Jun 2025

CVE-2025-52557: Mail-0 Zero · Improper Handling of Physical or Environmental Conditions

Affects Mail-0 ZeroSource CVE Database V5

Not known to be exploited · CVSS 8.6 High · fixed in 0.81 : patch Mail-0 Zero soon.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

8.6High

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 35% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.81

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: Passive
Vulnerable system confidentiality: High
Vulnerable system integrity: High
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

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

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: Passive: Successful exploitation of this vulnerability requires limited interaction by the targeted user with the vulnerable system and the attacker’s payload. These interactions would be considered involuntary and do not require that the user actively subvert protections built into the vulnerable system.
Vulnerable system confidentiality: High: There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Vulnerable system 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 vulnerable system. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the vulnerable system.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 21 Jun 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 2026-10-25.

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
GitHubmail-0/Zero`pkg:github/mail-0/Zero`Other threats	Affected =0.8	Fixed in–

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AI-suggested

1. Immediate upgrade to Mail-0's Zero version 0.81 or later, where the vulnerability has been patched, is the most effective mitigation. 2. Implement strict email content filtering and sanitization at the mail gateway level to detect and block emails containing suspicious JavaScript or embedded scripts before they reach end users. 3. Employ Content Security Policy (CSP) headers and other browser-based security controls to restrict execution of inline scripts in webmail interfaces. 4. Educate users about the risks of interacting with unexpected or suspicious emails, emphasizing caution with links or embedded content. 5. Monitor logs for unusual session activity or multiple concurrent sessions from different IP addresses, which could indicate session hijacking attempts. 6. Consider deploying multi-factor authentication (MFA) for email access to reduce the impact of session hijacking by requiring additional verification steps. 7. Conduct regular security assessments and penetration testing focused on email platforms to identify and remediate similar vulnerabilities proactively. 8. If upgrading immediately is not feasible, temporarily disable or restrict JavaScript execution in the email client interface, if configurable, to reduce attack surface.

Description

Mail-0's Zero is an open-source email solution. In version 0.8 it's possible for an attacker to craft an email that executes javascript leading to session hijacking due to improper sanitization. This issue has been patched in version 0.81.

Impact

For European organizations using Mail-0's Zero version 0.8, this vulnerability poses a significant risk to the confidentiality and integrity of email communications. Successful exploitation could allow attackers to hijack user sessions, leading to unauthorized access to sensitive emails, internal communications, and potentially further lateral movement within the organization's network. This could result in data breaches, leakage of confidential information, and disruption of business operations. Given that email is a critical communication tool, compromised accounts could also be used to launch phishing campaigns internally or externally, amplifying the threat. The impact is particularly severe for sectors with high regulatory requirements around data protection, such as finance, healthcare, and government institutions in Europe, where unauthorized data access can lead to legal penalties under GDPR and other regulations. Additionally, session hijacking could undermine trust in organizational communication systems, affecting reputation and operational continuity.

CWE-1384Improper Handling of Physical or Environmental Conditions (opens in a new tab)
Class weakness
The product does not properly handle unexpected physical or environmental conditions that occur naturally or are artificially induced.
Requirements
In requirements, be specific about expectations for how the product will perform when it exceeds physical and environmental boundary conditions, e.g., by shutting down.
Architecture and Design · Implementation
Where possible, include independent components that can detect excess environmental conditions and have the capability to shut down the product.
Architecture and Design · Implementation
Where possible, use shielding or other materials that can increase the adversary's workload and reduce the likelihood of being able to successfully trigger a security-related failure.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 21 Jun 2025, 11:51 UTC

WeaknessesCWE-1384

Technical details

References

Community reviews

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