Is CVE-2026-48126 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-48126 being exploited in the wild.

How severe is CVE-2026-48126?

High severity, with a CVSS score of 8.2, published 26 May 2026.

Which products and versions are affected?

github.com/xyproto/algernon (Go) <= 1.17.7, SEMVER:introduced=0,fixed=1.17.8; Xyproto Algernon <= 1.17.7.

Is there a fix for CVE-2026-48126?

Yes. github.com/xyproto/algernon (Go): upgrade to 1.17.8 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-48126 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-48126?

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.

CVE-2026-48126: xyproto Algernon path traversal and RCE via Host header

Q: Is there a fix for CVE-2026-48126?

Yes. github.com/xyproto/algernon (Go): upgrade to 1.17.8 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-48126 attacked?

It is attacked over the network, in a software library.

Q: Am I affected by CVE-2026-48126?

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.

CVE-2026-48126 · Severity: high · CVSS 8.2 · Published 2026-05-26

Algernon is a web server and application engine. A vulnerability in how it handles web requests allows an attacker to bypass security boundaries and access files outside of the intended web folder. This could lead to the theft of sensitive configuration files or, in some cases, allow the attacker to run malicious commands on the server.

Technologies: github.com/xyproto/algernon (Go), Xyproto Algernon. Vendors: Go, Xyproto.

Quick answers

Is CVE-2026-48126 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-48126 being exploited in the wild.
How severe is CVE-2026-48126?: High severity, with a CVSS score of 8.2, published 26 May 2026.
Which products and versions are affected?: github.com/xyproto/algernon (Go) <= 1.17.7, SEMVER:introduced=0,fixed=1.17.8; Xyproto Algernon <= 1.17.7.
Is there a fix for CVE-2026-48126?: Yes. github.com/xyproto/algernon (Go): upgrade to 1.17.8 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-48126 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-48126?: 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.

How to fix

github.com/xyproto/algernon (Go): upgrade to 1.17.8 or later
```
go get github.com/xyproto/algernon@v1.17.8
```

Technical details

A path traversal vulnerability exists in Algernon's request handler when the `--domain` or `--letsencrypt` flags are enabled. The application uses `filepath.Join` to combine the document root with the client-provided `Host` header without validation. An attacker can provide a `Host: ..` header to traverse to the parent directory of the document root. This allows for arbitrary file disclosure, directory listing, and remote code execution if the attacker can trigger the execution of `.lua` files located in the parent directory. The issue is fixed in version 1.17.8.

Affected products

xyproto algernon <= 1.17.7

Identifiers

CVE-2026-48126
GHSA-jc3j-x6pg-4hmv
GO-2026-5460

Timeline

2026-05-24: disclosed
2026-05-26: advisory: NVD publication
2026-06-23: patched: GitHub Advisory published and reviewed

References

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