External risk intelligence

Microsoft HEIF Image Extensions Out-of-Bounds Read Vulnerability.

CVE advisorySeverity: CRITICAL (CVSS 9.1)

CVE-2025-62821

This vulnerability affects a client-side image processing extension. It requires a user to open a specially crafted image file, which is not a network-reachable service, edge gateway, or public-facing application endpoint in common deployment patterns.

Out-of-bounds Read

Microsoft Heif Image Extension

1.2.22.0

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

Microsoft's HEIF Image Extensions contain a critical vulnerability that could allow for unauthorized access to information and denial of service. This issue arises from an out-of-bounds read vulnerability within the image processing component, which could be triggered by a specially crafted image file.

Flaw in image handling can expose data.
Leadership should remember this for potential data risks.
Confirm relevance and exposure of this image extension.

Attack Path

How an attacker could exploit the issue

An attacker could lead a user to open a specially crafted image file, exploiting a flaw in how image data size is handled. This could cause a program to read beyond the allocated memory when processing the image, potentially leading to a crash or disclosure of sensitive information.

No authentication or user interaction needed.
Opening a malicious HEIF image file.
Information disclosure or denial of service.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could affect the integrity and availability of systems processing HEIF image files. When an attacker provides a specially crafted HEIF file, the Microsoft HEIF Image Extensions may encounter an out-of-bounds read, potentially leading to a crash or other service disruptions.

System crashes could occur.
Malformed HEIF files may trigger the flaw.
Application instability or denial of service.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in Microsoft HEIF Image Extensions impacts client-side operations, primarily concerning user interaction with specially crafted image files. Owners of endpoints where users might open such files, likely managed by endpoint or device management teams, should prioritize identifying affected systems. The first practical step is to confirm the presence and reachability of the vulnerable component and assess its business criticality before planning remediation.

Identify affected endpoints and ownership.
Verify user exposure to crafted images.
Plan targeted user-based mitigation.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is the Microsoft HEIF Image Extensions software?

This software component is a codec plugin for Windows that enables the operating system and applications to display and process High Efficiency Image File (HEIF) format images. It allows users to view photos that use advanced compression techniques, which provide high-quality images with smaller file sizes than traditional formats like JPEG.

What does an out-of-bounds read vulnerability mean for CVE-2025-62821?

It belongs to the CWE-125 weakness class, where software reads data past the end of an intended buffer. In this CVE, the code incorrectly calculates the size of image data, leading to a tiny memory allocation. When the program later tries to process the full image, it reads memory locations it shouldn't access, which can cause the application to crash or potentially reveal sensitive data from other parts of the system's memory.

How is this vulnerability triggered?

The flaw is triggered when a user opens a specially crafted, malicious HEIF image file with an application that utilizes this extension. Simply viewing a standard, legitimate HEIF image does not trigger the bug; the file must be intentionally structured to exploit the incorrect data size calculation within the extension's processing logic.

Is this vulnerability relevant to my network servers?

According to Halo Surface Signal, this is highly unlikely. The vulnerability affects a client-side extension, not a network-reachable service, edge gateway, or public-facing application. Because it requires a user to open a specific file, the primary risk lies on end-user devices rather than infrastructure components typically monitored for external network exposure.

What should I do if I have this software installed?

You should focus on identifying which endpoints in your environment have this extension installed. Since the issue is client-side, coordinate with your device management teams to verify where users might interact with untrusted image files. Assess the risk based on how often your systems process HEIF files from external or unverified sources, and ensure your standard update processes are in place to receive software patches.

References

github.com/hyunjungg/CVE-2025-62821

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.