CVE-2026-12503
Received Received - Intake

Improper Link Resolution in Loytec LINX-A64 Devices

Publication date: 2026-07-24

Last updated on: 2026-07-24

Assigner: Switzerland Government Common Vulnerability Program

Description
Improper Link Resolution (CWE-59) in `/usr/bin/larm_starter` in Loytec L-INX, L-GATE, L-ROC, L-IOB, L-DALI, L-VIS and L-PAD through 8.4.16 on LINX-A64 allows an authenticated `larmapp` attacker to make `/etc/passwd` writable by the `larmapp` group (leading to root privilege escalation) via a symlink attack on `/etc/lighttpd/ssl/server.pem`.

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Meta Information

Published
2026-07-24
Last Modified
2026-07-24
Generated
2026-07-24
AI Q&A
2026-07-24
EPSS Evaluated
N/A
NVD
CVE-2026-12503
EUVD
EUVD-2026-48591

Affected Vendors & Products

Showing 8 associated CPEs
Vendor Product Version / Range
loytec l-inx to 8.4.16 (inc)
loytec l-gate to 8.4.16 (inc)
loytec l-roc to 8.4.16 (inc)
loytec l-iob to 8.4.16 (inc)
loytec l-dali to 8.4.16 (inc)
loytec l-vis to 8.4.16 (inc)
loytec l-pad to 8.4.16 (inc)
loytec l-web to 8.4.16 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-59 The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

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Executive Summary

This vulnerability is an improper link resolution flaw (CWE-59) in Loytec devices. An authenticated attacker with larmapp privileges can exploit a symlink attack on /etc/lighttpd/ssl/server.pem to make /etc/passwd writable by the larmapp group. This leads to root privilege escalation due to incorrect permission handling in the set_perm() function.

Detection Guidance

Check for writable permissions on /etc/passwd by the larmapp group using: ls -l /etc/passwd. Verify if /etc/lighttpd/ssl/server.pem is a symlink pointing to /etc/passwd with: ls -l /etc/lighttpd/ssl/server.pem. Inspect larm_starter binary for improper symlink handling in set_perm() function.

Impact Analysis

An attacker could modify system files like /etc/passwd, potentially gaining root access. This could allow full control over the affected device, enabling further attacks or system compromise. The impact is severe due to the critical nature of system file tampering.

Compliance Impact

This vulnerability could lead to unauthorized system access, violating data integrity and confidentiality requirements in GDPR and HIPAA. Compromised systems may fail compliance audits due to inadequate security controls protecting sensitive data.

Mitigation Strategies

Upgrade affected LOYTEC products to firmware version 8.4.18 or later immediately. Remove write permissions from the larmapp group on /etc/passwd using chmod 644 /etc/passwd. Restrict larmapp user access until patching is complete.

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