VulnerabilityPublished 18 Dec 2024

CVE-2024-55492: Winmail Server · Cross-site Scripting

Source CVE Database V5

Not known to be exploited · CVSS 6.1 Medium.

Data as of 26 Oct 2026, 11:07 UTC

CVSS 3.1 base score

6.1Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Changed
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: 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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
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 18 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

Organizations should implement strict input validation and output encoding on all user-supplied data, particularly the 'f_user' parameter, to prevent injection of malicious scripts. Until an official patch is released by the vendor, administrators should consider deploying Web Application Firewalls (WAFs) with custom rules to detect and block suspicious payloads containing SVG or script tags in URL parameters. User awareness training to recognize phishing attempts can reduce the likelihood of successful exploitation. Monitoring web server logs for unusual or suspicious requests targeting the 'f_user' parameter can help detect attempted attacks. If possible, restrict access to the Winmail Server web interface to trusted networks or VPNs to limit exposure. Regularly check for vendor advisories and apply patches promptly once available. Additionally, implementing Content Security Policy (CSP) headers can mitigate the impact of XSS by restricting script execution sources.

Description

Winmail Server 4.4 is vulnerable to f_user=%22%3E%3Csvg%20onload Cross Site Scripting (XSS).

Impact

The primary impact of CVE-2024-55492 is the compromise of confidentiality and integrity for users interacting with vulnerable Winmail Server 4.4 instances. Attackers can execute arbitrary scripts in victims' browsers, potentially stealing session tokens, credentials, or other sensitive information accessible via the web interface. This can lead to unauthorized access or manipulation of user data. While availability is not affected, the reputational damage and potential data breaches can be significant for organizations relying on Winmail Server for email services. Since the vulnerability requires user interaction, phishing or social engineering attacks are likely exploitation vectors, increasing risk for organizations with less security awareness training. Enterprises with internet-facing Winmail Server deployments, especially those handling sensitive communications, face elevated risk. The medium severity score reflects a moderate but actionable threat that could facilitate further attacks if chained with other vulnerabilities or misconfigurations.

Summary

CVE-2024-55492 is a Cross-Site Scripting (XSS) vulnerability identified in Winmail Server version 4.4. The issue stems from insufficient input validation and output encoding of the 'f_user' parameter, which can be manipulated to inject malicious SVG elements containing an 'onload' event handler. When a victim accesses a crafted URL or interface that reflects this parameter, the embedded script executes in the context of the user's browser session. This vulnerability is classified under CWE-79, indicating a classic reflected XSS flaw. The CVSS v3.1 base score is 6.1, reflecting medium severity, with an attack vector of network (remote exploitation), low attack complexity, no privileges required, but requiring user interaction to trigger. The scope is changed (S:C), meaning the vulnerability affects components beyond the initially vulnerable component, potentially impacting the confidentiality and integrity of user data. The vulnerability does not impact availability. No patches or known exploits are currently available, but the risk remains for phishing or social engineering campaigns that lure users into clicking malicious links. The vulnerability could allow attackers to steal session cookies, perform actions on behalf of the user, or manipulate displayed content, undermining trust and security of the affected system.

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #1OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation · Architecture and Design
Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages.
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide…
OWASP Cheat Sheets
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Injection Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
OWASP ASVS 4.0.3
V5.3.3 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
XSS Using MIME Type Mismatch (opens in a new tab)
DOM-Based XSS (opens in a new tab)
Reflected XSS (opens in a new tab)
Stored XSS (opens in a new tab)
Cross-Site Scripting (XSS) (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/qtxz54/Vul/blob/main/XSS/Winmail-Server.md (opens in a new tab)

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 26 Feb 2026, 02:05 UTC

WeaknessesCWE-79

Technical details

References

Community reviews

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