---
id: CVE-2026-77581
title: BentoPDF is a client-side PDF toolkit that is self hostable
summary: >-
  BentoPDF is a client-side PDF toolkit that is self hostable. In 2.8.6 and
  earlier, the certificate and timestamp CORS proxy in
  cloudflare/cors-proxy-worker.js uses isPrivateOrReservedHost() to validate a
  supplied hostname separately from…
severity: high
cvss: 8.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L'
cwe:
  - CWE-918
vendor: alam00000
product: bentopdf
affected:
  - bentopdf < 2.8.7
published: '2026-09-24'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T16:17:10.943'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77581'
references:
  - url: >-
      https://github.com/alam00000/bentopdf/commit/45496fcd2ed6e02dcdde0d3839cc5024c091760c
    label: security-advisories@github.com
  - url: >-
      https://github.com/alam00000/bentopdf/commit/58cd1a8893bfe06e4a59a72adc2e7db00a8b9266
    label: security-advisories@github.com
  - url: 'https://github.com/alam00000/bentopdf/releases/tag/v2.8.7'
    label: security-advisories@github.com
  - url: >-
      https://github.com/alam00000/bentopdf/security/advisories/GHSA-5xjf-rr5x-pcfj
    label: security-advisories@github.com
  - url: >-
      https://github.com/alam00000/bentopdf/security/advisories/GHSA-5xjf-rr5x-pcfj
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-24T15:37:09.697885Z'
ingestedAt: '2026-09-24T15:45:56.658Z'
epss: 0.00266
epssPercentile: 0.16843
---

## Overview

BentoPDF is a client-side PDF toolkit that is self hostable. In 2.8.6 and earlier, the certificate and timestamp CORS proxy in cloudflare/cors-proxy-worker.js uses isPrivateOrReservedHost() to validate a supplied hostname separately from the DNS resolution used by fetch(targetUrl), allowing an attacker-controlled hostname to resolve to an internal or reserved destination after validation. A certificate-like path can satisfy ALLOWED_PATH_PATTERNS, and direct clients can forge the browser-oriented Origin header. Deployments without PROXY_SECRET skip the optional signature check, while the signature is an anti-abuse measure rather than a destination-security boundary. The proxy has a 10 MB response limit and can relay response bodies from reachable destinations. The advisory identifies both the official Worker deployment and self-hosted instances as impacted where the Worker execution environment can reach internal or reserved destinations. This vulnerability is fixed in 2.8.7.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.