CVE-2025-65018 is a heap buffer overflow vulnerability identified in the widely used libpng library, specifically affecting versions from 1.6.0 up to but not including 1.6.51. The flaw exists in the simplified API function png_image_finish_read, which is responsible for reading PNG images. When processing 16-bit interlaced PNG files with an 8-bit output format, the function improperly handles buffer boundaries, leading to out-of-bounds writes on the heap. This vulnerability arises due to incorrect calculations or insufficient boundary checks when converting or processing image data, allowing crafted PNG files to overwrite memory beyond the allocated buffer. The vulnerability is classified under CWE-787 (Out-of-bounds Write) and CWE-122 (Heap-based Buffer Overflow). Exploitation requires the victim to open or process a malicious PNG file, implying user interaction is necessary. The attack vector is local (AV:L), with low attack complexity (AC:L), no privileges required (PR:N), and user interaction required (UI:R). The impact affects integrity and availability, potentially causing application crashes or enabling code execution in certain contexts. Although no known exploits are currently reported in the wild, the vulnerability's high CVSS score (7.1) and the critical nature of libpng in many software ecosystems make timely patching essential. The issue was addressed in libpng version 1.6.51, which includes proper bounds checking and fixes to prevent heap overflow during image processing.

For European organizations, this vulnerability poses a significant risk particularly to those involved in software development, digital media, content management, and any sector relying on image processing tools that incorporate libpng. Exploitation could lead to application instability, denial of service, or potentially arbitrary code execution if combined with other vulnerabilities or exploited in complex attack chains. This can compromise the integrity of systems processing untrusted PNG images, such as web servers, content delivery platforms, and desktop applications. Given the widespread use of libpng in open-source and commercial software, the vulnerability could affect a broad range of products and services. The requirement for user interaction limits remote exploitation but does not eliminate risk, especially in environments where users frequently handle image files from external sources. The impact on availability and integrity could disrupt business operations, lead to data corruption, or facilitate further compromise of internal networks. Organizations in sectors like finance, government, media, and technology are particularly sensitive to such disruptions.

The primary mitigation is to upgrade all libpng instances to version 1.6.51 or later, where the vulnerability is patched. Organizations should conduct thorough software inventory and dependency analysis to identify all applications and libraries that include libpng, including indirect dependencies in third-party software. Implement strict file validation and sandboxing for applications that process PNG images, especially those exposed to untrusted sources. Employ runtime protections such as Address Space Layout Randomization (ASLR), Data Execution Prevention (DEP), and heap protection mechanisms to reduce exploitation impact. Educate users about the risks of opening untrusted image files and enforce policies restricting file sources. Monitor security advisories for any emerging exploits targeting this vulnerability and apply patches promptly. For critical systems, consider isolating image processing tasks or using alternative libraries until patched versions are deployed. Regularly update and patch all software components to minimize exposure to known vulnerabilities.