CVE-2026-80155: Path Traversal (CVSS 10)

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.

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CVSS v3.1 Score

10.0

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0103

Probability of exploitation

0.63%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-22 Path Traversal

References

Other References

https://revrb.net/2026/09/21/revrb-lantern.html https://ts.lantronix.com/ftp/SLC9000/9.7.0.2R1/ https://ts.lantronix.com/ftp/emg/EMG_7500/9.7.0.1R2/ https://ts.lantronix.com/ftp/emg/EMG_8500/9.7.0.1R2/ https://ts.lantronix.com/ftp/slc8000/9.7.0.5R2/ https://www.vulncheck.com/advisories/lantronix-autonomous-out-of-band-devices-unauthenticated-authentication-bypass-via-snprintf-path-truncation

Frequently Asked Questions

What is CVE-2026-80155? +

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. It has a CVSS v3.1 base score of 10.0 (CRITICAL).

How severe is CVE-2026-80155? +

CVE-2026-80155 has a CVSS v3.1 score of 10.0 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0103, placing it in the 1th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-80155? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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