Critical File handling

CVE-2026-12503 — Loytec LINX firmware: Improper Link Resolution in /usr/bin/larm_starter

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`.

Published Jul 24, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: NCSC.ch

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

Technical severity (critical)+10

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

—

No EPSS score.

Affects

Loytec

L-DALI and 7 more

CVSS base

9.2

Critical · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Loytec L-DALI, Loytec L-GATE, Loytec L-INX…).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (file handling), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Loytec	L-DALI	≤ 8.4.16	Vulnerable	CVE Program (cve.org) e CISA ADP
Loytec	L-GATE	≤ 8.4.16	Vulnerable	CVE Program (cve.org) e CISA ADP
Loytec	L-INX	≤ 8.4.16	Vulnerable	CVE Program (cve.org) e CISA ADP
Loytec	L-IOB	≤ 8.4.16	Vulnerable	CVE Program (cve.org) e CISA ADP
Loytec	L-PAD	≤ 8.4.16	Vulnerable	CVE Program (cve.org) e CISA ADP
Loytec	L-ROC	≤ 8.4.16	Vulnerable	CVE Program (cve.org) e CISA ADP
Loytec	L-VIS	≤ 8.4.16	Vulnerable	CVE Program (cve.org) e CISA ADP
Loytec	LIP-ME20xC	≤ 8.4.16	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Local

Attack complexity

Low

Attack requirements

None

Privileges required

High

User interaction

None

Scope

Confidentiality (vulnerable system)

High

Integrity (vulnerable system)

High

Availability (vulnerable system)

High

Confidentiality (subsequent)

None

Integrity (subsequent)

High

Availability (subsequent)

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
9.2	CVSS 4.0	Critical	—	—	vulnerability@ncsc.ch via NIST National Vulnerability Database
9.2	CVSS 4.0	Critical	—	—	NCSC.ch via CVE Program (cve.org) e CISA ADP

CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

(score shown at the top: vulnerability@ncsc.ch)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-59 · Link Following

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
Monitor file creation in web directories and paths with traversal sequences (../).

endpoint telemetry (EDR)file integrity (FIM)

Timeline

What happened to this CVE, newest first.

2026
Affected products added · loytec/lip-me20xc, loytec/l-inx, loytec/l-gate, loytec/l-roc, loytec/l-iob, loytec/l-dali, loytec/l-vis, loytec/l-pad
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
CVSS changed · 9.2
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Deferred
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Jul 24, 2026 · NCSC.ch

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

1 on the record

www.loytec.com/support/product-security/advisories/8520-dibt-cve-20260526-0002-symli
vendor-advisory, NIST National Vulnerability Database

Elsewhere on this site

Loytec
every CVE for this vendor

File handling
same class

CWE-59
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-55731 Loytec LINX firmware: Unchecked input for loop condition in the SNMP agent Jul 24, 2026
High CVE-2026-55732 Loytec LINX firmware: Out-of-bounds Read in BACnet packet parsing (bacdt_datetime_to_tod) Jul 24, 2026
Low CVE-2026-55728 Loytec LINX firmware: Stack-based Buffer Overflow in cmd_ipaddr_conflict Jul 24, 2026
High CVE-2026-12504 Loytec LINX firmware: Improper Authentication in PAM configuration Jul 24, 2026
High CVE-2026-12502 Loytec LINX firmware: Improper Privilege Management in /usr/bin/ltsudo Jul 24, 2026
High CVE-2026-12496 Loytec LINX firmware: Unauthenticated stored XSS in OPC XML-DA server Jul 24, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No FIRST EPSS score.
No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-12503 is "Loytec LINX firmware: Improper Link Resolution in /usr/bin/larm_starter", rated Critical. It affects L-DALI (Loytec); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.2 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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