How severe is CVE-2026-12503?

CVE-2026-12503 has a CVSS 4.0 base score of 9.2, rated critical severity.

Is CVE-2026-12503 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-12503?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-12503 published?

CVE-2026-12503 was published on 2026-07-24 and last updated on 2026-07-27.

CVE-2026-12503

CVE-2026-12503 is a critical-severity vulnerability with a CVSS 4.0 base score of 9.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-59.

Key facts

Severity: Critical (CVSS 4.0 base score 9.2)
EPSS exploit prediction: 0% (3rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-59
Published: 2026-07-24
Last modified: 2026-07-27

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`.

Frequently asked questions

What is CVE-2026-12503?: 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`.
How severe is CVE-2026-12503?: CVE-2026-12503 has a CVSS 4.0 base score of 9.2, rated critical severity.
Is CVE-2026-12503 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-12503?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-12503 published?: CVE-2026-12503 was published on 2026-07-24 and last updated on 2026-07-27.

References

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

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