CVE-2026-25968: 
C# vulnerability analysis and mitigation

CVE-2026-25968 is a stack-based buffer overflow vulnerability in ImageMagick's MSL (Magick Scripting Language) attribute processing code (msl.c) that can lead to memory corruption and potentially arbitrary code execution. It affects ImageMagick versions prior to 7.1.2-15 (7.x branch) and prior to 6.9.13-40 (6.9.x branch), as well as Magick.NET NuGet packages prior to version 14.10.3. The vulnerability was published on February 24, 2026, with the GitHub Security Advisory (GHSA-3mwp-xqp2-q6ph) authored by maintainer dlemstra and credited to researcher ylwango613. The CVSS v3.1 base score is 9.8 (Critical) per Feedly/NVD assessment, though the GitHub Advisory rates it 7.4 (High) with higher attack complexity (GitHub Advisory, Red Hat Bugzilla).

The root cause is a classic stack-based buffer overflow (CWE-121, CWE-787) in msl.c, the file responsible for processing MSL (Magick Scripting Language) attributes. When ImageMagick processes an MSL file containing an attribute with an excessively long value, the value is copied into a fixed-size stack buffer without adequate bounds checking (CWE-120), causing a stack buffer overflow and out-of-bounds write. AddressSanitizer output from the advisory confirms a WRITE of size 1 at an address beyond the stack buffer boundary (stack-buffer-overflow on address 0x7ffdb8c76984), indicating a byte-by-byte overflow pattern. No public proof-of-concept exploit code has been disclosed as of the time of this report (GitHub Advisory, GitHub Advisory DB).

Successful exploitation can result in memory corruption leading to arbitrary code execution on the system running ImageMagick, with potential for full confidentiality, integrity, and availability compromise. An unauthenticated remote attacker can trigger the overflow by supplying a specially crafted MSL file or attribute value to any service that processes images via ImageMagick, such as web applications, content management systems, or image conversion pipelines. Depending on the deployment context, exploitation could enable data exfiltration, unauthorized file modification, or denial of service through process crash (GitHub Advisory, Red Hat Bugzilla).

1. Reconnaissance: Identify services or web applications that accept user-supplied image files and process them using ImageMagick (e.g., image upload endpoints, thumbnail generators). Confirm the target is running a vulnerable version (ImageMagick < 7.1.2-15 or < 6.9.13-40) using version disclosure banners or error messages.
2. Craft malicious MSL file: Create an MSL (Magick Scripting Language) XML file containing an attribute with an excessively long string value designed to overflow the fixed-size stack buffer in msl.c. The payload length must exceed the buffer boundary to trigger the overflow.
3. Deliver the payload: Submit the crafted MSL file to the target service — for example, by uploading it as an image file to a web application that invokes ImageMagick for processing, or by passing it directly to the convert or magick command-line tool if local access is available.
4. Trigger memory corruption: ImageMagick processes the MSL attribute, copies the oversized value into the fixed-size stack buffer without bounds checking, causing a stack buffer overflow and out-of-bounds write.
5. Achieve code execution (if exploitable): Depending on stack layout, memory protections (ASLR, stack canaries), and the specific overflow pattern, an attacker may be able to overwrite the return address or function pointers to redirect execution to attacker-controlled code, achieving remote code execution as the ImageMagick process user (GitHub Advisory).

• File System: Presence of unexpected or malformed .msl XML files in upload directories or temporary image processing folders; files with unusually large attribute values in MSL format.
• Logs: Application or web server logs showing image upload or processing requests with abnormally large payloads; ImageMagick crash logs or core dumps in /tmp or the application working directory; AddressSanitizer or segmentation fault messages in system logs referencing msl.c.
• Process: Unexpected child processes spawned by the ImageMagick process (e.g., sh, bash, curl, wget) following image processing operations; ImageMagick processes consuming abnormal CPU or memory.
• Network: Outbound connections from the web/application server to unknown external IPs shortly after image processing events, which may indicate post-exploitation activity such as reverse shell establishment or data exfiltration.

The primary remediation is to upgrade ImageMagick to version 7.1.2-15 or later (7.x branch) or 6.9.13-40 or later (6.9.x branch). For Magick.NET users, upgrade to version 14.10.3 or later. Linux distribution users should apply vendor-provided security updates: Ubuntu (USN-8069-1), Debian (DSA-6158-1, DSA-6159-1, DLA-4497-1), SUSE, and openSUSE have all released patched packages. If immediate patching is not possible, restrict or disable access to ImageMagick-based image processing services, and implement input validation to reject MSL files or unusually large attribute values. Oracle users should apply the April 2026 Critical Patch Update (GitHub Advisory, Oracle CPU, Ubuntu Advisory).

The vulnerability received standard coverage across Linux distribution security channels, with Ubuntu, Debian, SUSE, openSUSE, and Amazon Linux all issuing security advisories and patched packages within weeks of disclosure. Oracle included it in the April 2026 Critical Patch Update. Qualys published a review of the Oracle CPU that referenced this CVE. No notable independent researcher commentary or significant social media discussion has been identified beyond routine vulnerability tracking and distribution advisories (Oracle CPU, Ubuntu Advisory).