Quick answers
- Is This vulnerability exploited in the wild?
- No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
- How severe is This vulnerability?
- Medium severity, with a CVSS score of 5.3, published 19 May 2026.
- Which products and versions are affected?
- github.com/xyproto/algernon (Go) <= 1.17.6; Xyproto Algernon <= 1.17.6.
- Is there a fix for This vulnerability?
- A patch was published on 2026-05-19: Version 1.17.7 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is This vulnerability attacked?
- It is attacked over the network, in a network appliance.
- Am I affected?
- Check whether you run github.com/xyproto/algernon (Go) or Xyproto Algernon at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The auto-refresh functionality in Algernon utilizes a Server-Sent Events (SSE) handler that fails to implement any authentication or authorization checks. The handler, located in the recwatch component, binds to all interfaces and sets 'Access-Control-Allow-Origin: *', making it accessible to any client capable of establishing a TCP connection. Because the listener operates on its own http.ServeMux, it bypasses standard middleware protections like permissions2. An attacker can connect to the SSE endpoint (typically on port 5553) to receive a real-time stream of filesystem events, revealing sensitive filenames and directory layouts. This issue is addressed in version 1.17.7.
Affected products
- xyproto algernon <= 1.17.6
Timeline
- 2026-05-12: disclosed
- 2026-05-19: advisory
- 2026-05-19: patched: Version 1.17.7 released