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CVE-2026-77581— BentoPDF: SSRF in cors-proxy-worker.js via DNS-based hostname allowlist bypass

Quick assessment

Affected
alam00000 bentopdf
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

BentoPDF 是一个可自托管的客户端 PDF 工具包。在版本 2.8.6 及更早版本中，cloudflare/cors-proxy-worker.js 中用于处理证书和时间戳的 CORS 代理使用 isPrivateOrReservedHost() 函数对提供的 hostname 进行单独验证，而该验证与 fetch(targetUrl) 实际使用的 DNS 解析过程相互独立。攻击者可以利用这一缺陷，在验证通过后，使一个由其控制的 hostname 解析到一个内部或保留地址。此外，类似证书路径的内容可以满足 A

CVSS 8.6 · High EPSS 0.27% · P17

Affected Version Matrix 1

VendorProduct Version RangeStatus
alam00000 bentopdf < 2.8.7 affected
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I. Basic Information for CVE-2026-77581

Vulnerability Information
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Vulnerability Title
BentoPDF: SSRF in cors-proxy-worker.js via DNS-based hostname allowlist bypass
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
alam00000 bentopdf < 2.8.7 -

II. Public POCs for CVE-2026-77581

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III. Intelligence Information for CVE-2026-77581

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Patches & Fixes for CVE-2026-77581 (2)

Vendor Advisories for CVE-2026-77581 (1)

IV. Related Vulnerabilities

Same product: bentopdf
Same vendor: alam00000
Same weakness: CWE-918

V. Comments for CVE-2026-77581

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