Vulnerability · Published May 26, 2026 · Assigned by GitHub_M
CVE-2026-45728Algernon: Single-file mode unconditionally enables debug mode
High 7.5
In plain English
A high-severity security flaw in algernon from xyproto. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/xyproto/algernon | 1.17.7 | GHSA-fwqx-8365-9983 |
| Go | github.com/xyproto/algernon | 1.17.7 | GO-2026-5385 |
Affected products (as reported)
Weakness: CWE-209, CWE-489, CWE-540, CWE-1188 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
References
- https://github.com/xyproto/algernon/security/advisories/GHSA-fwqx-8365-9983 x_refsource_CONFIRM