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Fencer Intel
medium 5.5

CVE-2026-39031 json

Lansweeper lsrunase 2.0 and lsencrypt 2.0 use RC4 encryption with a hardcoded 142-byte static key array to encrypt credentials.

published 4mo ago modified 4mo ago also EUVD-2026-39939

cvss
5.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 0%
public exploits
0
none known

Summary

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.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
4mo ago

Exploit prediction

0.09% chance of exploitation in the next 30 days, higher than 0% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • usermode.net https://usermode.net/cve/lansweeper_lsrunase2_lsencrypt2_cve.pdf referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/user6400/cve-2026-39031-lansweeper-lsrunase2-lsencrypt2 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CNA 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Classification

Weakness
  • CWE-321 Use of Hard-coded Cryptographic Key

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.