Overview
CVE-2025-59820 is a medium-severity security vulnerability affecting KDE Krita versions prior to 5.2.13. This vulnerability resides in the TGA image import functionality and can be exploited by loading a specially crafted TGA file, leading to a heap-based buffer overflow. Successful exploitation could result in application crash, arbitrary code execution, or information disclosure. Users of Krita are strongly advised to upgrade to version 5.2.13 or later to mitigate this risk.
Technical Details
The vulnerability is located in the plugins/impex/tga/kis_tga_import.cpp file, specifically within the KisTgaImport component responsible for parsing and processing TGA image files. The core issue is that the code doesn’t properly validate the pixel dimensions specified within the TGA file header. A manipulated TGA file can specify negative values for the number of pixels, causing the application to allocate an insufficient buffer on the heap. When the application subsequently attempts to write image data into this undersized buffer, it results in a heap-based buffer overflow. The flawed logic can be summarized as follows:
// Vulnerable Code Snippet (Simplified) - for illustration only
// ...
int width = tga_header.width; // Potentially negative value
int height = tga_header.height; // Potentially negative value
size_t image_size = width * height * bytes_per_pixel; // Calculation with negative values
buffer = allocate_memory(image_size); // Small buffer if width or height is negative
memcpy(buffer, tga_image_data, actual_data_size); // Overflow likely to happen here
The commit 6d3651ac4df88efb68e013d21061de9846e83fe8 addresses this by adding proper validation of the pixel dimensions to ensure they are positive values before allocation and processing.
CVSS Analysis
The Common Vulnerability Scoring System (CVSS) score for CVE-2025-59820 is 6.7 (MEDIUM). The CVSS vector associated with this score is likely to be something similar to AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H. This breaks down as follows:
- AV:L (Attack Vector: Local): An attacker needs local access to the system to exploit the vulnerability.
- AC:L (Attack Complexity: Low): The vulnerability is relatively easy to exploit.
- PR:N (Privileges Required: None): No privileges are required to exploit the vulnerability; simply opening the malicious TGA file is sufficient.
- UI:R (User Interaction: Required): User interaction is required, specifically the user must open a malicious TGA file.
- S:U (Scope: Unchanged): The vulnerability affects the application itself, not the entire system.
- C:L (Confidentiality: Low): There is limited potential for information disclosure.
- I:L (Integrity: Low): There is limited potential to modify data.
- A:H (Availability: High): The vulnerability can cause a denial of service (application crash) or potentially arbitrary code execution leading to system compromise.
Possible Impact
Successful exploitation of CVE-2025-59820 can have the following consequences:
- Application Crash: The most likely outcome is a crash of the Krita application.
- Arbitrary Code Execution: In certain circumstances, an attacker might be able to leverage the heap overflow to execute arbitrary code on the victim’s system. This would require a deeper understanding of the application’s memory layout and the ability to craft a sophisticated exploit.
- Information Disclosure: The overflow could potentially lead to the disclosure of sensitive information stored in memory.
Mitigation
The primary mitigation for CVE-2025-59820 is to upgrade Krita to version 5.2.13 or later. This version includes the necessary fix to properly validate TGA file headers and prevent the heap overflow.
- Upgrade Krita: Download and install the latest version of Krita from the official website.
- Exercise Caution: Be cautious when opening TGA files from untrusted sources.
- Verify File Origins: If possible, verify the integrity and origin of TGA files before opening them.
