CVE-2026-39031

Description

Lansweeper lsrunase 2.0 and lsencrypt 2.0 use RC4 encryption with a hardcoded 142-byte static key array to encrypt credentials. An 8-character prefix is stored in cleartext alongside the ciphertext. This allows an attacker with local access to recover any encrypted password to plaintext using a single SHA-1 hash and RC4 decryption operation, with no brute force required.

CVSS v3.1 Score

5.5

MEDIUM

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

EPSS — Exploit Prediction

0.0009

Probability of exploitation

0.01%

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-321 CWE-321

References

Other References

https://github.com/user6400/cve-2026-39031-lansweeper-lsrunase2-lsencrypt2 https://usermode.net/cve/lansweeper_lsrunase2_lsencrypt2_cve.pdf https://github.com/user6400/cve-2026-39031-lansweeper-lsrunase2-lsencrypt2 https://usermode.net/cve/lansweeper_lsrunase2_lsencrypt2_cve.pdf

Frequently Asked Questions

What is CVE-2026-39031? +

Lansweeper lsrunase 2.0 and lsencrypt 2.0 use RC4 encryption with a hardcoded 142-byte static key array to encrypt credentials. An 8-character prefix is stored in cleartext alongside the ciphertext. This allows an attacker with local access to recover any encrypted password to plaintext using a single SHA-1 hash and RC4 decryption operation, with no brute force required. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-39031? +

CVE-2026-39031 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0009, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-39031? +

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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