CVE-2026-80155: Lantronix Autonomous Out-of-Band Devices Unauthenticated Authentication Bypass via snprintf Path Truncation

Severity: critical (CVSS 10.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-22 · updated 2026-09-24
Weakness: CWE-22

Description

Lantronix SLC8000 before firmware v9.7.0.5, SLC9000 before firmware v9.7.0.2, EMG8500/EMG7500 before firmware v9.7.0.1, and all firmware versions of SLB882/SLCx-03/SLCx-02 contain an authentication bypass vulnerability in the web management portal upload endpoint that allows unauthenticated attackers to read sensitive configuration files and upload files to arbitrary filesystem locations, leading to remote code execution. The web configuration server constructs the session cookie file path using snprintf with a fixed-size buffer; by supplying a cookie value of a specific length an attacker causes the path to truncate at the required delimiter and leverages path traversal to redirect authentication validation to an arbitrary on-disk file such as the local user database, bypassing all session checks. Attackers can use this vulnerability to achieve complete loss of confidentiality, integrity, and availability on the affected device and potentially impact downstream serial-connected devices.

Affected products

LANTRONIX EMG7500: before 9.7.0.1 — fixed in 9.7.0.1
LANTRONIX EMG8500: before 9.7.0.1 — fixed in 9.7.0.1
LANTRONIX SLB882: all versions
LANTRONIX SLC8000: before 9.7.0.5 — fixed in 9.7.0.5
LANTRONIX SLC9000: before 9.7.0.2 — fixed in 9.7.0.2
LANTRONIX SLCx-02: all versions
LANTRONIX SLCx-03: all versions

How to fix

Upgrade to a fixed version: LANTRONIX EMG7500 9.7.0.1; LANTRONIX EMG8500 9.7.0.1; LANTRONIX SLC8000 9.7.0.5; LANTRONIX SLC9000 9.7.0.2. Check the vendor advisory for mitigations.

References

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