CVE-2026-77581 BentoPDF: SSRF in cors-proxy-worker.js via DNS-based hostname allowlist bypass
Attacker can bypass hostname validation in BentoPDF's CORS proxy to access internal resources via DNS rebinding, exposing sensitive data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-77581?
CVE-2026-77581 is a high-severity server-side request forgery vulnerability in alam00000 bentopdf, published on 24 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-918
Which versions are affected by CVE-2026-77581?
How do I fix CVE-2026-77581?
No fix has been published for CVE-2026-77581 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-77581 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77581 exists.
Sources
Also known as GHSA-5xjf-rr5x-pcfj.