# 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.

- **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-5xjf-rr5x-pcfj

## 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 (Server-Side Request Forgery)

## 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.

## Is CVE-2026-77581 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77581 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-77581 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77581 exists.

Affected product: alam00000 bentopdf. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-77581/ (Markdown: https://insights.sbomify.com/CVE-2026-77581/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-77581
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-77581
- OSV: https://osv.dev/vulnerability/CVE-2026-77581

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-77581/
Summaries are generated and may contain mistakes; the official description above is the record.