CVE-2024-43439VulnerabilityPublished 24 Apr 2025

CVE-2024-43439: fedora · Cross-site Scripting

Source CVE Database V5

Not known to be exploited · CVSS 5.4 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

5.4Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 28% 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:U/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
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: 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: 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 24 Apr 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 2026-10-26.

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

AI-suggested

1. Apply official Moodle updates as soon as they are released that address this vulnerability, ensuring all affected versions are upgraded to patched releases. 2. In the absence of immediate patches, implement web application firewall (WAF) rules to detect and block suspicious input patterns in URL parameters or POST data related to H5P error messages. 3. Conduct input validation and output encoding on all user-supplied data reflected in error messages, specifically sanitizing HTML and JavaScript content to prevent script injection. 4. Educate users and administrators about the risks of clicking on untrusted links, especially those purporting to be from Moodle or related educational platforms. 5. Monitor Moodle logs and web traffic for unusual patterns indicative of attempted XSS exploitation, such as repeated error message triggers with suspicious payloads. 6. Limit the exposure of Moodle instances to only trusted networks or users where feasible, reducing the attack surface. 7. Review and harden Content Security Policy (CSP) headers to restrict execution of inline scripts and reduce the impact of reflected XSS. 8. Regularly audit and test Moodle installations for XSS vulnerabilities using automated scanners and manual penetration testing.

Description

A flaw was found in moodle. H5P error messages require additional sanitizing to prevent a reflected cross-site scripting (XSS) risk.

Impact

The primary impact of CVE-2024-43439 is on the confidentiality and integrity of user sessions within Moodle platforms. Successful exploitation could allow attackers to execute arbitrary JavaScript in the context of the victim's browser, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of the user. This can undermine trust in the affected Moodle instance and lead to data leakage or unauthorized access to educational resources. Since Moodle is widely used by educational institutions, government training programs, and corporate learning environments, the scope of affected users can be large. The vulnerability does not affect system availability directly but can facilitate further attacks that degrade service or compromise data. The requirement for user interaction (clicking a malicious link) limits automated exploitation but does not eliminate risk, especially in phishing-prone environments. Organizations failing to address this vulnerability may face reputational damage, compliance issues, and increased risk of targeted attacks against their learning management infrastructure.

Summary

CVE-2024-43439 is a reflected cross-site scripting (XSS) vulnerability identified in Moodle, a widely used open-source learning management system. The vulnerability specifically involves the handling of error messages generated by the H5P interactive content plugin or module within Moodle. These error messages fail to properly sanitize user-supplied input before reflecting it back in the web interface, which can allow an attacker to inject malicious JavaScript code. When a victim clicks on a crafted URL or interacts with a manipulated input that triggers the vulnerable error message, the malicious script executes in the victim's browser context. This can lead to theft of session cookies, user impersonation, or other client-side attacks. The vulnerability affects Moodle versions 0, 4.2, 4.3, and 4.4, indicating it spans multiple recent releases. The CVSS 3.1 base score is 5.4, reflecting a medium severity with network attack vector, low complexity, no privileges required, but requiring user interaction. The impact primarily affects confidentiality and integrity, with no direct availability impact. No known exploits have been reported in the wild as of the publication date. The vulnerability is categorized under CWE-79 (Improper Neutralization of Input During Web Page Generation), a common XSS weakness. The lack of patch links suggests a fix may be pending or distributed through Moodle's regular updates. Given Moodle's extensive use in educational institutions worldwide, this vulnerability poses a risk to user data and session security if exploited.

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

Community reviews

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 26 Feb 2026, 07:45 UTC

WeaknessesCWE-79

Technical details

References

Community reviews

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