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CVE-2026-45728— Algernon: Single-file mode unconditionally enables debug mode

Quick assessment

Affected
xyproto algernon
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

algernon是Alexander F. Rødseth个人开发者的一个 Web 服务器。 Algernon 1.17.7之前版本存在安全漏洞，该漏洞源于单文件模式下调试模式强制启用，导致错误响应中泄露文件绝对路径和完整字节内容，可能导致客户端获取服务器端源代码。

CVSS 7.5 · High EPSS 0.42% · P34

Possible ATT&CK Techniques 1 AI

T1530 · Data from Cloud Storage

Affected Version Matrix 1

VendorProduct Version RangeStatus
xyproto algernon < 1.17.7 affected
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I. Basic Information for CVE-2026-45728

Vulnerability Information
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Vulnerability Title
Algernon: Single-file mode unconditionally enables debug mode
Source: CVE Program / CVE List V5
Vulnerability Description
Algernon is a small self-contained pure-Go web server. Prior to 1.17.7, when Algernon is invoked with a single file path instead of a directory, singleFileMode is set to true and debugMode is forcibly enabled. debugMode activates the PrettyError renderer, which on any Lua or template error response dumps the absolute path of the file that errored, complete byte contents of that file, and exception or parser error text. This response is served with HTTP 200 OK to whoever sent the request that triggered the error. Any client able to reach the server and able to provoke a runtime error in the served script obtains the full server-side source of that script and of any sibling Lua data file consulted during the request. This vulnerability is fixed in 1.17.7.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
通过错误消息导致的信息暴露
Source: CVE Program / CVE List V5
Vulnerability Title
algernon 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
algernon是Alexander F. Rødseth个人开发者的一个 Web 服务器。 Algernon 1.17.7之前版本存在安全漏洞，该漏洞源于单文件模式下调试模式强制启用，导致错误响应中泄露文件绝对路径和完整字节内容，可能导致客户端获取服务器端源代码。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
xyproto algernon < 1.17.7 -

II. Public POCs for CVE-2026-45728

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 6497 chars
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Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
In-depth vulnerability mechanism
Trigger conditions & impact
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Exploit chain & mitigation
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III. Intelligence Information for CVE-2026-45728

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Vendor Advisories for CVE-2026-45728 (1)

Same Patch Batch · xyproto · 2026-05-26 · 7 CVEs total

CVE-2026-45721 9.0 CRITICAL Algernon: handler.lua discovery walks parent directories above the server root
CVE-2026-48126 8.2 HIGH Algernon: Host header path traversal in --domain mode reads files and runs Lua from parent
CVE-2026-46430 4.3 MEDIUM Algernon: Auto-refresh SSE event server binds to all interfaces by default on Linux/macOS
CVE-2026-46431 4.3 MEDIUM Algernon: Auto-refresh SSE event server sets Access-Control-Allow-Origin: *
CVE-2026-43981 Algernon: Race Condition in handle() shared LState
CVE-2026-43982 Algernon: Path traversal file write via savein()

IV. Related Vulnerabilities

Same product: algernon
Same vendor: xyproto
Same weakness: CWE-209

V. Comments for CVE-2026-45728

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