CVE-2026-25897: 
C# vulnerability analysis and mitigation

CVE-2026-25897 is an integer overflow vulnerability in ImageMagick's SUN image decoder that can lead to an out-of-bounds heap write on 32-bit systems and builds. It affects ImageMagick versions prior to 7.1.2-15 (7.x branch) and prior to 6.9.13-40 (6.x branch), as well as Magick.NET NuGet packages prior to version 14.10.3. The vulnerability was published on February 23–24, 2026, with patches released simultaneously. The GitHub Security Advisory (GHSA-6j5f-24fw-pqp4) assigns a CVSS v3.1 score of 6.5 (Moderate), while Feedly's aggregated data reflects a higher estimate of 9.8 (Critical) — the authoritative vendor score from the advisory is 6.5 (GitHub Advisory, Red Hat Bugzilla).

The root cause is an integer overflow (CWE-190) in ImageMagick's SUN image file decoder, which on 32-bit systems or builds causes a subsequent heap-based buffer overflow (CWE-122). When processing a specially crafted SUN image, the decoder performs an arithmetic operation that overflows a 32-bit integer, resulting in an undersized heap buffer allocation; subsequent writes then exceed the allocated region. The AddressSanitizer output included in the advisory confirms a WRITE of size 1 at an out-of-bounds heap address (0xf190b50e), triggered in a 32-bit build environment. The vulnerability is exploitable over the network without authentication or user interaction, provided the attacker can supply a malicious image to a service or application using a vulnerable ImageMagick build (GitHub Advisory, Github Advisory).

Successful exploitation can result in denial of service (application crash), information disclosure through memory leaks, and potentially remote code execution, depending on heap layout and attacker control over the overflow. The vulnerability is specifically triggered on 32-bit systems or builds, limiting the affected population to environments where ImageMagick is compiled or deployed as a 32-bit binary. Applications that automatically process user-supplied images — such as web services, content management systems, or media pipelines — are at elevated risk of remote exploitation (GitHub Advisory, Feedly).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation as of the time of reporting (Github Advisory). The EPSS score is approximately 0.038% (0.000380), indicating a low near-term exploitation probability. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. No threat actor attribution has been reported.

1. Reconnaissance: Identify services or applications that accept image uploads and process them using a 32-bit build of ImageMagick (versions prior to 7.1.2-15 or 6.9.13-40), such as web applications, image conversion APIs, or media processing pipelines.
2. Craft malicious SUN image: Create a specially crafted SUN-format image file with header fields designed to trigger an integer overflow in the decoder's size calculation, causing an undersized heap buffer to be allocated.
3. Deliver the payload: Submit the crafted image to the target application via an upload endpoint, API call, or any other mechanism that causes ImageMagick to decode the SUN image on a 32-bit build.
4. Trigger out-of-bounds write: The integer overflow causes ImageMagick to write image data beyond the allocated heap buffer, potentially corrupting adjacent heap metadata or data structures.
5. Achieve objective: Depending on heap layout and exploitation precision, the attacker may cause a denial of service (crash), leak memory contents, or — in advanced scenarios — achieve remote code execution by controlling heap corruption to redirect execution flow (GitHub Advisory).

• Logs: Application logs showing crashes or unexpected termination of ImageMagick processes (convert, magick) when processing SUN-format image files; error messages referencing heap corruption or segmentation faults.
• Process: Unexpected crashes of image processing worker processes on 32-bit systems; AddressSanitizer output (if enabled) showing heap-buffer-overflow with WRITE operations in the SUN decoder code path.
• File System: Presence of unusual or malformed .sun image files in upload directories or temporary processing folders that do not conform to standard SUN image format specifications.
• Network: Repeated submission of SUN-format image files (magic bytes: 0x59 0xA6 0x6A 0x95) to image processing endpoints, especially from unexpected or external sources.

Update ImageMagick to version 7.1.2-15 or later (7.x branch) or 6.9.13-40 or later (6.x branch). For Magick.NET users, upgrade to version 14.10.3 or later. As interim mitigations, restrict image processing to trusted sources, disable SUN image format support in ImageMagick's policy.xml if not required, and run ImageMagick in a sandboxed or containerized environment with reduced privileges. Network segmentation to limit exposure of image-processing services is also recommended (GitHub Advisory, Github Advisory).

The vulnerability was disclosed by maintainer dlemstra via the ImageMagick GitHub Security Advisory on February 23, 2026, with patches released simultaneously. Red Hat, Ubuntu, Debian, SUSE, and openSUSE all issued security advisories and updated packages in the weeks following disclosure, indicating broad Linux distribution response. No notable independent researcher commentary or significant social media discussion has been identified beyond standard vulnerability tracking and distribution patching activity (Red Hat Bugzilla, Github Advisory).