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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.

PUBLISHED Reserved 2026-05-13 | Published 2026-05-26 | Updated 2026-05-26 | Assigner GitHub_M




HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Problem types

CWE-209: Generation of Error Message Containing Sensitive Information

CWE-489: Active Debug Code

CWE-540: Inclusion of Sensitive Information in Source Code

CWE-1188: Insecure Default Initialization of Resource

Product status

< 1.17.7
affected

References

github.com/...gernon/security/advisories/GHSA-fwqx-8365-9983 exploit

github.com/...gernon/security/advisories/GHSA-fwqx-8365-9983

cve.org (CVE-2026-45728)

nvd.nist.gov (CVE-2026-45728)

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