External risk intelligence

imgproxy ICO Loader Integer Overflow Heap Buffer Overflow

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-123614

imgproxy is commonly deployed as a public-facing image processing service or API endpoint that accepts and processes external user-supplied images. Because the vulnerable ICO loader component is a core function of this edge-facing application, the attack surface is frequently exposed to the public internet in standard deployment patterns.

Buffer Overflow

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory concerns a flaw in imgproxy's image processing capability that could allow an attacker to disrupt service or potentially execute code. The vulnerability is triggered by a specially crafted ICO image file, which can exploit an integer overflow to corrupt memory. While the technical details involve heap buffer overflows and code execution, the high-level concern is the potential for unauthorized access or disruption to services relying on this image processing software.

Attackers can crash services with bad images.
Confirms potential exposure of public-facing services.
Assess relevance and exposure to business operations.

Attack Path

How an attacker could exploit the issue

An attacker can target the imgproxy application by sending a specially crafted ICO image to its processing endpoint. This image contains a value that triggers an integer overflow in the ICO loader. When this overflow occurs, it can corrupt memory on the server, potentially leading to the application crashing or allowing the attacker to execute their own code.

No authentication required.
Crafted ICO image triggers overflow.
Remote code execution or crash.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could affect imgproxy services that load ICO files, potentially leading to the disruption of image processing or the execution of unauthorized code. The risk arises when an attacker crafts a malicious ICO file that exploits an integer overflow in the ICO loader, corrupting the service's memory.

Heap memory corruption.
Exploitation via crafted ICO file.
Denial of service or code execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

Real-world ownership for this vulnerability likely falls to teams managing the imgproxy service, which could include platform, infrastructure, or application teams depending on deployment. The first practical step is to identify all instances of imgproxy, determine their exposure and business criticality, and then confirm the accountable owner for each to plan remediation.

App owners or Platform teams.
Verify public exposure and criticality.
Plan targeted remediation or vendor coordination.

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 imgproxy?

imgproxy is a specialized server application used to resize, process, and convert images on the fly. It is commonly deployed as a middleware service or API gateway that accepts raw image files from various sources, transforms them to fit specific UI requirements, and serves them to end users, effectively offloading complex image manipulation tasks from the primary web application.

What does CVE-2026-123614 mean?

This CVE identifies a heap-based buffer overflow flaw (CWE-122) within the imgproxy ICO file loader. In technical terms, it stems from an integer overflow where an improperly sized data field causes the software to allocate insufficient memory. This memory corruption can allow an attacker to crash the service or potentially force the application to execute arbitrary, unauthorized code.

How is this vulnerability triggered?

The issue is triggered when imgproxy attempts to process a specifically crafted ICO image file designed to exploit the integer overflow. Simply having the service running is not enough; the attacker must successfully cause the application to load and parse the malicious file. Standard, well-formed ICO images that do not contain the manipulated data size values do not trigger this specific memory error.

Is my imgproxy instance at risk?

According to Halo Surface Signal, this vulnerability is highly relevant if your instance is public-facing. Because imgproxy is typically deployed as an edge service to process external, user-supplied images, public internet exposure is a standard pattern that elevates risk. Internal-only instances that do not process untrusted or external image traffic have a significantly reduced attack surface.

What should I do first to address this?

Begin by creating an inventory of all imgproxy deployments within your environment to identify which versions are active. Once you have a list, prioritize instances that are accessible from the public internet or process external input. Coordinate with the teams managing those specific assets to plan for an update to a patched version, ensuring you verify the criticality of each service before applying changes.

References

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.