VulnerabilityPublished 15 Dec 2025

CVE-2023-53891: Blackcat CMS · Cross-site Scripting

Affects Blackcat CMSSource CVE Database V5

Not known to be exploited · CVSS 5.1 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 4.0 base score

5.1Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 15% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: Passive
Vulnerable system confidentiality: Low
Vulnerable system integrity: Low
Vulnerable system availability: None
Subsequent system confidentiality: Low
Subsequent system integrity: Low
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: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
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: 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 Vulnerable System.
Vulnerable system 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 to the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system 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 Subsequent System.
Subsequent system 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 to the Subsequent 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 15 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
blackcat-cms Blackcat CMS	Affected =1.4	Fixed in–

AI-suggested

Apply patches or updates from Blackcat CMS vendor as soon as they become available to address CVE-2023-53891.
Until patches are released, restrict CMS user permissions to the minimum necessary, limiting page modification rights to trusted users only.
Implement strict input validation and output encoding on all user-supplied content within the CMS, especially in the page modification interface, to neutralize potentially malicious scripts.
Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers accessing the CMS pages.
Conduct regular security audits and code reviews focusing on input handling and output rendering in the CMS.
Monitor CMS logs and user activity for unusual behavior indicative of attempted exploitation.
Educate CMS users about the risks of XSS and safe content editing practices.
Consider deploying web application firewalls (WAF) with rules to detect and block XSS payloads targeting the CMS.

Description

CVE-2023-53891 is a stored cross-site scripting (XSS) vulnerability in Blackcat CMS version 1.4 that allows authenticated users to inject malicious JavaScript into page content. When other users view the compromised page, the injected scripts execute, potentially leading to session hijacking, credential theft, or unauthorized actions. The vulnerability requires authentication and some user interaction, and it has a medium severity CVSS score of 5.1. No known exploits are currently reported in the wild. European organizations using Blackcat CMS 1.4, especially those with multiple authenticated users managing content, are at risk. Mitigation involves applying patches once available, restricting user permissions, implementing input sanitization, and monitoring CMS activity. Countries with higher adoption of Blackcat CMS or significant web content management needs, such as Germany, France, and the UK, may be more affected.

Impact

For European organizations using Blackcat CMS 1.4, this vulnerability poses a risk primarily to the confidentiality and integrity of user sessions and data. Attackers with authenticated access can embed malicious scripts that execute in other users' browsers, potentially leading to credential theft, session hijacking, or unauthorized actions performed under the victim's identity. This can compromise sensitive information and disrupt trust in web applications. While the vulnerability does not directly affect system availability, successful exploitation could lead to further attacks or data leakage. Organizations with multiple content editors or users with CMS access are at higher risk. The medium severity rating reflects the need for authentication and user interaction, which somewhat limits the attack surface but does not eliminate risk. Given the widespread use of CMS platforms in Europe for public-facing websites and intranets, exploitation could impact business operations, reputation, and compliance with data protection regulations such as GDPR if personal data is exposed.

Summary

CVE-2023-53891 identifies a stored cross-site scripting vulnerability in Blackcat CMS version 1.4. This vulnerability arises from improper neutralization of input during web page generation, specifically allowing authenticated users to inject malicious JavaScript payloads into page content via the page modification interface. When other users access the compromised pages, the injected scripts execute in their browsers, enabling attackers to perform actions such as session hijacking, stealing cookies or credentials, or conducting further attacks within the context of the victim's session. The vulnerability requires the attacker to have authenticated access to the CMS, which limits exploitation to users with some level of privilege. User interaction is necessary for the payload to execute, as it triggers when another user views the infected page. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required beyond authenticated user (PR:L), and user interaction required (UI:P). The impact on confidentiality and integrity is low to limited, with no direct availability impact. No patches or known exploits are currently publicly available, but the vulnerability is published and should be addressed promptly. The vulnerability is typical of stored XSS issues in content management systems where input sanitization and output encoding are insufficient or missing during page rendering.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 22 Dec 2025, 21:53 UTC

Technical details

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