CVE-2026-77581

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.

• https://github.com/alam00000/bentopdf/commit/45496fcd2ed6e02dcdde0d3839cc5024c091760c
• https://github.com/alam00000/bentopdf/commit/58cd1a8893bfe06e4a59a72adc2e7db00a8b9266
• https://github.com/alam00000/bentopdf/releases/tag/v2.8.7
• https://github.com/alam00000/bentopdf/security/advisories/GHSA-5xjf-rr5x-pcfj
• https://github.com/alam00000/bentopdf/security/advisories/GHSA-5xjf-rr5x-pcfj