CVE-2026-48126Public exploitNetwork attack vector

File disclosure and Lua execution via Host traversal

Published May 26, 2026 · Updated May 26, 2026

Path traversal in xyproto Algernon 1.17.7 and earlier allows remote attackers to read parent-directory files via a crafted Host header. The RegisterHandlers request handler passes GetDomain(req)'s unvalidated req.Host value to filepath.Join with the configured served directory. Exposure requires --domain or --letsencrypt; directory listing is direct, while shell-command execution requires an accessible Lua file in the parent directory.

CVSS severity8.2
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in xyproto Algernon 1.17.7 and earlier allows remote attackers to read parent-directory files via a crafted Host header. The RegisterHandlers request handler passes GetDomain(req)'s unvalidated req.Host value to filepath.Join with the configured served directory. Exposure requires --domain or --letsencrypt; directory listing is direct, while shell-command execution requires an accessible Lua file in the parent directory.

The record

CVE
CVE-2026-48126
Published
May 26, 2026
Updated
May 26, 2026
Vendor
xyproto
Product
Algernon
Classifications
CWE-23, CWE-644, CWE-22, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 26, 2026CVE publishedPublication date reported by the CVE source.
  2. May 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.17.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

xyproto · Algernonversion=< 1.17.8

Published CVSS scores

8.2GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-23Relative Path Traversal
CWE-644Improper Neutralization of HTTP Headers for Scripting Syntax
CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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