VulnerabilityPublished 21 Jul 2025Updated 22 Jul 2025

CVE-2025-51400: A Stored Cross-site Scripting (XSS)

Source CVE Database V5

Public exploit available (Exploit-DB) · CVSS 5.4 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

5.4Medium

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

EPSS: 0.9% chance of exploitation in 30 days – higher than 61% 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:C/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
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: 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: 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

t = 0 is the CVE’s publication on cve.org

Disclosed: evidence found.
CVE published 21 Jul 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
1 Exploit-DB entry, 1 day after disclosure
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

CVE ID reserved
by MITRE Corporation
16 Jun 2025, 35 days before disclosure
CVE published
on cve.org
21 Jul 2025, t = 0
In Threat Radar
record ingested
21 Jul 202519:16 UTC, the same day as disclosure
First Exploit-DB entry (opens in a new tab)
LiveHelperChat 4.61 - Stored Cross Site Scripting (XSS) via Personal Canned Messages
22 Jul 2025, 1 day after disclosure

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

Immediate mitigation should include restricting access to the Personal Canned Messages feature to only trusted and necessary users, minimizing the number of accounts that can inject content.
Implement strict input validation and output encoding on all user-supplied content within the Personal Canned Messages functionality to neutralize malicious scripts.
Monitor and audit usage of canned messages for suspicious or anomalous entries that could indicate attempted exploitation.
Apply the principle of least privilege to user roles within Live Helper Chat, ensuring users have only the permissions required for their tasks.
Encourage users to avoid clicking on suspicious links or interacting with unexpected messages within the chat interface.
7. Stay updated with vendor advisories for patches or updates addressing this vulnerability and apply them promptly once released. 8. Conduct security awareness training for support staff to recognize and report suspicious activity related to chat messages. 9. Review and harden session management and cookie security settings to reduce the impact of potential session hijacking.

Description

A stored cross-site scripting (XSS) vulnerability in the Personal Canned Messages of Live Helper Chat v4.60 allows attackers to execute arbitrary web scripts or HTML via injecting a crafted payload.

Impact

For European organizations using Live Helper Chat, this vulnerability poses a moderate risk primarily to the confidentiality and integrity of user sessions and data. Attackers exploiting this flaw could execute malicious scripts in the context of other users, potentially stealing session cookies, performing actions on behalf of users, or delivering further malware payloads. This could lead to unauthorized access to sensitive customer information, manipulation of support interactions, or reputational damage. Since Live Helper Chat is often integrated into customer-facing portals, exploitation could affect both internal support staff and external customers, increasing the attack surface. The requirement for attacker privileges and user interaction somewhat limits the ease of exploitation, but insider threats or compromised accounts could facilitate attacks. Additionally, the scope change indicates that the impact could extend beyond the immediate component, possibly affecting other integrated systems or data. European organizations with strict data protection regulations (e.g., GDPR) must be particularly cautious, as exploitation could lead to data breaches and regulatory penalties. The absence of known exploits in the wild provides a window for proactive mitigation before widespread attacks occur.

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

Loading reviews…

Exploitation evidence

Timeline

What to do

Description

AI analysisMachine-generated, updated 29 Jul 2025, 01:28 UTC

Public exploits and detection1 Exploit-DB entry

WeaknessesCWE-79

Technical details

References

Community reviews

Related threats