CVE-2025-66512 Vulnerability Analysis & Exploit Details

CVE-2025-66512
Vulnerability Scoring

5.4
/10
Significant Risk

Security assessments indicate that CVE-2025-66512 presents a notable risk, potentially requiring prompt mitigation.

Attack Complexity Details

  • Attack Complexity: Low
    Exploits can be performed without significant complexity or special conditions.
  • Attack Vector: Network
    Vulnerability is exploitable over a network without physical access.
  • Privileges Required: None
    No privileges are required for exploitation.
  • Scope: Unchanged
    Exploit remains within the originally vulnerable component.
  • User Interaction: Required
    User interaction is necessary for successful exploitation.

CVE-2025-66512 Details

Status: Received on 05 Dec 2025, 17:16 UTC

Published on: 05 Dec 2025, 17:16 UTC

CVSS Release: version 3

CVSS3 Source

security-advisories@github.com

CVSS3 Type

Secondary

CVSS3 Vector

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

CVE-2025-66512 Vulnerability Summary

CVE-2025-66512: Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server and Server Enterprise prior to 31.0.12 and 32.0.3, a missing sanitization allowed malicious users to circumvent the content security policy when a malicious user manages to trick a user it viewing an uploaded SVG outside of the Nextcloud Servers web page.

Assessing the Risk of CVE-2025-66512

Access Complexity Graph

The exploitability of CVE-2025-66512 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2025-66512

With low attack complexity and no required privileges, CVE-2025-66512 is an easy target for cybercriminals. Organizations should prioritize immediate mitigation measures to prevent unauthorized access and data breaches.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2025-66512, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2025-66512, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2025-66512 has no significant impact on data confidentiality.
  • Integrity: Low
    Exploiting CVE-2025-66512 may cause minor changes to data without severely impacting its accuracy.
  • Availability: Low
    CVE-2025-66512 may slightly degrade system performance without fully affecting service availability.

CVE-2025-66512 References

External References

CWE Common Weakness Enumeration

CWE-80

CAPEC Common Attack Pattern Enumeration and Classification

  • XSS Targeting Non-Script Elements CAPEC-18 This attack is a form of Cross-Site Scripting (XSS) where malicious scripts are embedded in elements that are not expected to host scripts such as image tags (<img>), comments in XML documents (< !-CDATA->), etc. These tags may not be subject to the same input validation, output validation, and other content filtering and checking routines, so this can create an opportunity for an adversary to tunnel through the application's elements and launch a XSS attack through other elements. As with all remote attacks, it is important to differentiate the ability to launch an attack (such as probing an internal network for unpatched servers) and the ability of the remote adversary to collect and interpret the output of said attack.
  • PHP Remote File Inclusion CAPEC-193 In this pattern the adversary is able to load and execute arbitrary code remotely available from the application. This is usually accomplished through an insecurely configured PHP runtime environment and an improperly sanitized "include" or "require" call, which the user can then control to point to any web-accessible file. This allows adversaries to hijack the targeted application and force it to execute their own instructions.
  • XSS Through HTTP Query Strings CAPEC-32 An adversary embeds malicious script code in the parameters of an HTTP query string and convinces a victim to submit the HTTP request that contains the query string to a vulnerable web application. The web application then procedes to use the values parameters without properly validation them first and generates the HTML code that will be executed by the victim's browser.
  • XSS Through HTTP Headers CAPEC-86 An adversary exploits web applications that generate web content, such as links in a HTML page, based on unvalidated or improperly validated data submitted by other actors. XSS in HTTP Headers attacks target the HTTP headers which are hidden from most users and may not be validated by web applications.

Protect Your Infrastructure against CVE-2025-66512: Combat Critical CVE Threats

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