Cyber Posture

CVE-2026-48126

High
Microsoft: not affectedMSmacOS: not affectedMacLinux: not affectedLnxMobile: not affectedMobNetwork: not affectedNetApplication: not affectedAppOther: affectedOth

Published: 26 May 2026

Published
26 May 2026
Modified
26 May 2026
KEV Added
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Patch
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CVSS Score 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
EPSS Score 0.0007 20.3th percentile
Risk Priority 16 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-48126 is a high-severity Path Traversal (CWE-22) vulnerability. Its CVSS base score is 8.2 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 20.3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 2 other techniques.
Threat & Defense Details

Likely Mitigating ControlsAI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-10 Information Input Validation
addresses: CWE-22

Validates pathnames and filenames to prevent traversal outside intended directories.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1059.011 Lua Execution
Adversaries may abuse Lua commands and scripts for execution.
attack.mitre.org →
T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
Why these techniques?

Path traversal in public web server enables remote exploitation (T1190) for local file access (T1005) and Lua script execution (T1059.011).

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD 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…

more

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.

Deeper analysisAI

Automated synthesis unavailable for this CVE.

Details

CWE(s)
CWE-22CWE-23CWE-644
OWASP Top 10 Web 2025
A01:2025A05:2025

EU & UK References

References