VulnerabilityPublished 2 Dec 2025

CVE-2025-65858: calibre-web · XSS

Affects calibre-webSource CVE Database V5

Not known to be exploited · CVSS 3.5 Low.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

3.5Low

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: High
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: High: The attacker is authorized with (i.e., requires) privileges that provide significant (e.g., administrative) control over the vulnerable component that could affect component-wide settings and files.
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 2 Dec 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 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

Affected software

Product	Affected	Fixed in
GitHubkhanhduy155/calibre-web`pkg:github/khanhduy155/calibre-web`Other threats	Affected =0.6.25	Fixed in–

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AI-suggested

Restrict user creation privileges strictly to trusted administrators to reduce the attack surface.
Implement input validation and sanitization on the 'username' field to prevent injection of malicious scripts.
Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts within the application.
Monitor and audit user creation activities and access to the /ajax/listusers endpoint for suspicious behavior.
If possible, disable or restrict access to the /ajax/listusers endpoint until a patch is available.
Educate users about the risks of clicking on untrusted links or accessing endpoints that may trigger malicious scripts.
Regularly update Calibre-Web to the latest version once patches addressing this vulnerability are released.
Consider deploying web application firewalls (WAF) with rules to detect and block XSS payloads targeting this endpoint.

Description

CVE-2025-65858 is a stored Cross-Site Scripting (XSS) vulnerability in Calibre-Web v0.6.25 that allows attackers with user creation privileges to inject malicious JavaScript into the username field. This payload is stored unsanitized and executed when the /ajax/listusers endpoint is accessed, potentially leading to limited confidentiality and integrity impacts. The vulnerability requires authenticated access and user interaction to trigger. Although the CVSS score is low (3.5), the flaw could be leveraged in targeted attacks within environments using Calibre-Web. No known exploits are currently reported in the wild, and no patches have been published yet. European organizations using Calibre-Web should be aware of this vulnerability and implement mitigations to prevent exploitation. Countries with higher adoption of Calibre-Web or with strategic interest in digital libraries and document management may be more affected.

Impact

For European organizations using Calibre-Web, this vulnerability could allow an attacker with user creation privileges to execute malicious scripts in the context of other users accessing the /ajax/listusers endpoint. This could lead to theft of session cookies, unauthorized actions, or information disclosure limited to the application scope. While the impact is low severity, organizations handling sensitive or proprietary digital content may face risks to data confidentiality and integrity. The requirement for authenticated access and user interaction reduces the likelihood of widespread exploitation but does not eliminate risk in environments with multiple users or less stringent access controls. Additionally, if Calibre-Web is integrated into larger document management or digital library systems, the vulnerability could be leveraged as part of a multi-stage attack. The absence of patches means organizations must rely on mitigations until an official fix is released.

Summary

CVE-2025-65858 identifies a stored Cross-Site Scripting (XSS) vulnerability in Calibre-Web version 0.6.25. The vulnerability arises from improper input sanitization of the 'username' field during user creation, allowing an attacker with authenticated privileges to inject malicious JavaScript code. This malicious payload is stored persistently in the application database and is executed when the /ajax/listusers endpoint is accessed, which likely returns a list of users in a format that renders the injected script. The attack vector requires the attacker to have the ability to create users, indicating a need for at least some level of authenticated access (PR:H). Additionally, user interaction is required to trigger the payload execution (UI:R), as the victim must access the affected endpoint. The vulnerability impacts confidentiality and integrity to a limited extent, as the attacker could potentially steal session tokens or perform actions on behalf of other users within the scope of the application. Availability is not impacted. The CVSS vector (AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:L/A:N) reflects network attack vector, low attack complexity, high privileges required, user interaction needed, unchanged scope, and low confidentiality and integrity impacts. No patches or known exploits are currently available. The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation).

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/KhanhDuy155/calibre-web-CVE-2025-65858/blob/main/CVE-2025-65858.md (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 9 Dec 2025, 14:36 UTC

WeaknessesCWE-79

Technical details

References

Community reviews

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