What is CVE-2026-44040?

CVE-2026-44040 is a medium-severity vulnerability in Uvnc Ultravnc, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 4.8/10. Published 2026-07-01.

How severe is CVE-2026-44040?

Medium severity. CVSS v3 base score is 4.8 out of 10.

Vulnerability in Uvnc Ultravnc

CVE-2026-44040

UltraVNC through 1.8.2.2 uses a cryptographically weak pseudo-random number generator to produce VNC authentication challenge bytes. In rfb/vncauth.c:119-129, the vncRandomBytes() function seeds libc rand() with time(0) + getpid() + rand()…

CVSS v3 metric

CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N.

Affected products

Uvnc Ultravnc — versions 0

Weakness classification (CWE)

CWE-338 — Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

References

33c584b5-0579-4c06-b2a0-8d8329fcab9c (vendor-advisory)
33c584b5-0579-4c06-b2a0-8d8329fcab9c (product)

Frequently asked questions

What is CVE-2026-44040?: CVE-2026-44040 is a medium-severity vulnerability in Uvnc Ultravnc, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 4.8/10. Published 2026-07-01.
How severe is CVE-2026-44040?: Medium severity. CVSS v3 base score is 4.8 out of 10.