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CVE-2026-48126

8.2 · HIGH

Algernon is a small self-contained pure-Go web server.

Published May 26, 2026CWE-22EPSS 0.50%

Overview

CVE-2026-48126 is a high-severity vulnerability. It was published on May 26, 2026 and has a CVSS 3.1 base score of 8.2 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.2, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

Algernon is a small self-contained pure-Go web server. Prior to 1.17.8, when algernon is started with --domain (or --letsencrypt, which silently turns on --domain at engine/flags.go:372), the request handler resolves the served directory by joining the configured --dir with the value of the client-supplied Host header. The join is performed by filepath.Join with no validation, so a Host: .. header walks one level above the document root. Subsequent file resolution then exposes everything in that parent directory — arbitrary file read, full directory listing, and, if any .lua file is present, server-side Lua execution. This vulnerability is fixed in 1.17.8.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/xyproto/algernon/security/advisories/GHSA-jc3j-x6pg-4hmvGitHubgithub.com/xyproto/algernon/security/advisories/GHSA-jc3j-x6pg-4hmv

How CyberStrike helps

Frequently asked questions

What is CVE-2026-48126?

CVE-2026-48126 is a high-severity vulnerability. It was published on May 26, 2026 and has a CVSS 3.1 base score of 8.2 (HIGH).

How severe is CVE-2026-48126?

This vulnerability has a CVSS 3.1 base score of 8.2, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-48126?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-48126?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-48126 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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