alam00000 BentoPDF up to 2.8.6 CORS Proxy cors-proxy-worker.js isPrivateOrReservedHost cross-domain policy

Summaryinfo

A vulnerability was found in alam00000 BentoPDF up to 2.8.6. It has been rated as problematic. The affected element is the function isPrivateOrReservedHost of the file cloudflare/cors-proxy-worker.js of the component CORS Proxy. Performing a manipulation results in cross-domain policy. This vulnerability is reported as CVE-2026-77581. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as problematic has been found in alam00000 BentoPDF up to 2.8.6. This affects the function isPrivateOrReservedHost of the file cloudflare/cors-proxy-worker.js of the component CORS Proxy. The manipulation with an unknown input leads to a cross-domain policy vulnerability. CWE is classifying the issue as CWE-942. The product uses a cross-domain policy file that includes domains that should not be trusted. This is going to have an impact on confidentiality. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-77581 since 08/20/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available.

Upgrading to version 2.8.7 eliminates this vulnerability.

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Productinfo

Vendor

• alam00000

Name

• BentoPDF

Version

• 2.8.0
• 2.8.1
• 2.8.2
• 2.8.3
• 2.8.4
• 2.8.5
• 2.8.6

Website

• Product: https://github.com/alam00000/bentopdf/

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