Orta CVSS 6.5
CVE-2026-44040: Ultravnc: güvenlik açığı
Açıklama (NVD)
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() and generates a 16-byte challenge. The combined seed space is approximately 31 bits (libc rand() internal state) and is entirely determined by publicly-observable values (wall-clock time and process ID). An attacker who can observe the authentication exchange can enumerate the seed space and predict the challenge within seconds, enabling forgery or offline brute-forcing of responses. Note: on Windows, the active code path may use vncEncryptBytes2.cpp which calls CryptGenRandom; reachability on shipped Windows binaries requires compile-graph verification and is under investigation.
Özet bilgiler
- Ürün
- Uvnc Ultravnc
- CVSS v3.1
- 6.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N - EPSS
- %0,40 (yüzdelik 34)
- CWE
- CWE-338
- Yama
- Yok / bilinmiyor
Etkilenen sürümler
| Ürün | Başlangıç | Bitiş | Düzeltildi |
|---|---|---|---|
| uvnc-ultravnc | — | 1.8.2.2 | — |