CVE-2026-25636 Vulnerability Analysis & Exploit Details

CVE-2026-25636
Vulnerability Scoring

8.2
/10
Severe Risk

Cybersecurity professionals consider CVE-2026-25636 an immediate threat requiring urgent mitigation.

Attack Complexity Details

  • Attack Complexity: Low
    Exploits can be performed without significant complexity or special conditions.
  • Attack Vector: Local
    Vulnerability requires local system access.
  • Privileges Required: None
    No privileges are required for exploitation.
  • Scope: Changed
    Successful exploitation can impact components beyond the vulnerable component.
  • User Interaction: Required
    User interaction is necessary for successful exploitation.

CVE-2026-25636 Details

Status: Undergoing Analysis

Published on: 06 Feb 2026, 21:16 UTC

CVSS Release: version 3

CVSS3 Source

security-advisories@github.com

CVSS3 Type

Secondary

CVSS3 Vector

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

CVE-2026-25636 Vulnerability Summary

CVE-2026-25636: calibre is an e-book manager. In 9.1.0 and earlier, a path traversal vulnerability in Calibre's EPUB conversion allows a malicious EPUB file to corrupt arbitrary existing files writable by the Calibre process. During conversion, Calibre resolves CipherReference URI from META-INF/encryption.xml to an absolute filesystem path and opens it in read-write mode, even when it points outside the conversion extraction directory. This vulnerability is fixed in 9.2.0.

Assessing the Risk of CVE-2026-25636

Access Complexity Graph

The exploitability of CVE-2026-25636 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-2026-25636

With low attack complexity and no required privileges, CVE-2026-25636 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-2026-25636, 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-2026-25636, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2026-25636 has no significant impact on data confidentiality.
  • Integrity: High
    CVE-2026-25636 could allow unauthorized modifications to data, potentially affecting system reliability and trust.
  • Availability: High
    CVE-2026-25636 can disrupt system operations, potentially causing complete denial of service (DoS).

CVE-2026-25636 References

External References

CWE Common Weakness Enumeration

CWE-94

CAPEC Common Attack Pattern Enumeration and Classification

  • Code Injection CAPEC-242 An adversary exploits a weakness in input validation on the target to inject new code into that which is currently executing. This differs from code inclusion in that code inclusion involves the addition or replacement of a reference to a code file, which is subsequently loaded by the target and used as part of the code of some application.
  • Leverage Executable Code in Non-Executable Files CAPEC-35 An attack of this type exploits a system's trust in configuration and resource files. When the executable loads the resource (such as an image file or configuration file) the attacker has modified the file to either execute malicious code directly or manipulate the target process (e.g. application server) to execute based on the malicious configuration parameters. Since systems are increasingly interrelated mashing up resources from local and remote sources the possibility of this attack occurring is high.
  • Manipulating User-Controlled Variables CAPEC-77 This attack targets user controlled variables (DEBUG=1, PHP Globals, and So Forth). An adversary can override variables leveraging user-supplied, untrusted query variables directly used on the application server without any data sanitization. In extreme cases, the adversary can change variables controlling the business logic of the application. For instance, in languages like PHP, a number of poorly set default configurations may allow the user to override variables.

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