CVE-2026-55577: ImageMagick MVG Decoder Heap Buffer Overflow (CVSS 5.9)

Technical summary

The vulnerability exists in ImageMagick's MVG decoder implementation, where insufficient bounds checking allows an attacker to trigger a heap buffer overflow during image parsing. The flaw is classified under CWE-787 (out-of-bounds write), with contributing factors in exception handling (CWE-754) and resource management (CWE-755). The CVSS 3.1 vector (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H) indicates remote exploitability with high complexity requirements, yielding a medium severity rating of 5.9. Successful exploitation results in denial of service through memory corruption rather than data exfiltration or system compromise.

Business impact

Organizations relying on ImageMagick for image processing workflows—including web applications, content management systems, automated image resizing services, and batch processing pipelines—face service disruption risk. An attacker could craft malicious images to crash backend services, causing availability loss. While the vulnerability does not enable privilege escalation or data theft, repeated denial-of-service attacks could disrupt production operations, particularly in image-heavy platforms or automated processing environments.

Affected systems

ImageMagick versions prior to 6.9.13-51 (6.x legacy series) and 7.1.2-26 (7.x current series) are vulnerable. Both stable and development branches are affected. Any system embedding or calling ImageMagick to process untrusted image files is at risk, including containerized deployments, cloud-based image services, and on-premises image processing infrastructure.

Exploitability

Exploitation requires network access and the ability to supply a crafted MVG image to a vulnerable ImageMagick instance. The attack complexity is rated as high, indicating that specific malformed image characteristics must be met to reliably trigger the buffer overflow. No exploitation code has been publicly disclosed, and the vulnerability is not tracked in CISA's Known Exploited Vulnerabilities catalog. However, the remote, unauthenticated attack vector means that web-facing image upload or processing services are legitimate attack surfaces.

Remediation

Patch ImageMagick to version 6.9.13-51 or later for the legacy series, or version 7.1.2-26 or later for the current series. Organizations using distribution-provided packages should verify that their package manager offers updated builds. For development environments, update via official source repositories or package managers (apt, yum, brew, etc.). Until patching is complete, restrict untrusted image uploads or disable MVG format processing if not required.

Patch guidance

Verify the version of ImageMagick currently deployed by running `identify -version` or equivalent. For package manager installations, update using standard tools (e.g., `apt update && apt upgrade imagemagick` on Debian/Ubuntu systems). For containerized deployments, rebuild images from updated base OS layers or patched ImageMagick container images. For source builds, pull from the official ImageMagick repository and compile versions 6.9.13-51, 7.1.2-26, or later. Test patching in non-production environments first to verify compatibility with dependent applications.

Detection guidance

Monitor ImageMagick process logs and application error logs for crashes or segmentation faults coinciding with image upload or processing events. Network detection is difficult without payload signatures, as the malicious content is embedded in crafted MVG image files. Host-based detection can flag ImageMagick crashes using standard monitoring tools (e.g., systemd journal, syslog). If MVG format processing is unnecessary for your use case, disable it at the application level to eliminate attack surface. Web application firewalls may be configured to block file uploads with suspicious MVG headers, though such rules require careful tuning.

Why prioritize this

Despite medium CVSS severity, prioritization depends on deployment context. Organizations processing user-supplied images should treat this as elevated priority because remote, unauthenticated attackers can trigger denial of service. Environments where ImageMagick processes only internal or trusted image sources face lower risk. The high attack complexity and lack of public exploits reduce immediate threat, but the absence from KEV status means no known active exploitation pressure. Recommend patching within 30 days for externally exposed services, 60 days for internal deployments.

Risk score, explained

The CVSS 3.1 score of 5.9 reflects a remote, unauthenticated denial-of-service vector with high attack complexity. No confidentiality or integrity impact is possible; availability impact is high. The network-accessible attack vector combined with the lack of privilege or user interaction requirements elevates concern for web-facing services. However, the high complexity—requiring specifically malformed MVG payloads—and the absence of public proof-of-concept exploits prevent a higher score. Organizations with strict image validation or format restrictions can reasonably assess their actual risk as lower than the baseline score.

Frequently asked questions