What is the CVSS score of CVE-2026-25635?

CVE-2026-25635 has a CVSS 3.1 base score of 8.6 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H. EPSS exploitation probability: 0.2%.

Which versions of Windows are affected by CVE-2026-25635?

Calibre versions prior to 9.2.0 contain a critical vulnerability in the CHM reader that enables attackers to write arbitrary files to systems where users have access permissions.. A patch is available.

Is there a public PoC exploit available for CVE-2026-25635?

Yes, a public proof-of-concept exploit is available for CVE-2026-25635. Prioritise patching immediately. EPSS: 0.2%.

How to fix or mitigate CVE-2026-25635?

Within 24 hours: Identify all systems running Calibre versions prior to 9.2.0 using asset inventory tools and disable CHM file handling if not business-critical. Within 7 days: Deploy Calibre 9.2.0 or later across all affected systems; prioritize user-facing and shared systems first. Within 30 days: Complete patch deployment across the entire environment and verify through vulnerability scanning.

Windows CVE-2026-25635

HIGH

Path Traversal (CWE-22)

2026-02-06 security-advisories@github.com

Windows RCE Path Traversal Red Hat Calibre Suse Calibre Ebook

8.6

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

8.6 HIGH

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

SUSE

HIGH

qualitative

Red Hat

8.6 HIGH

qualitative

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

Attack Vector

Local

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:54 vuln.today

PoC Detected

Feb 17, 2026 - 21:27 vuln.today

Public exploit code

Patch released

Feb 17, 2026 - 21:27 nvd

Patch available

CVE Published

Feb 06, 2026 - 21:16 nvd

HIGH 8.6

DescriptionGitHub Advisory

calibre is an e-book manager. Prior to 9.2.0, Calibre's CHM reader contains a path traversal vulnerability that allows arbitrary file writes anywhere the user has write permissions. On Windows (haven't tested on other OS's), this can lead to Remote Code Execution by writing a payload to the Startup folder, which executes on next login. This vulnerability is fixed in 9.2.0.

AnalysisAI

Remote code execution in Calibre prior to version 9.2.0 through a path traversal flaw in the CHM reader allows local attackers to write arbitrary files with user permissions, enabling payload execution via the Windows Startup folder. Public exploit code exists for this vulnerability. Windows users should upgrade to Calibre 9.2.0 or later to remediate the risk.

Technical ContextAI

Classified as CWE-22 (Path Traversal). Affects Calibre. calibre is an e-book manager. Prior to 9.2.0, Calibre's CHM reader contains a path traversal vulnerability that allows arbitrary file writes anywhere the user has write permissions. On Windows (haven't tested on other OS's), this can lead to Remote Code Execution by writing a payload to the Startup folder, which executes on next login. This vulnerability is fixed in 9.2.0.