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Fencer Vulns
critical 9.8

CVE-2019-8258 json

UltraVNC revision 1198 has a heap buffer overflow vulnerability in VNC client code which results code execution.

published 2019-03-05 7 y ago modified 2026-06-17 4 mo ago also EUVD-2019-17656

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.4%
EPSS 4.4% chance of exploitation in 30 days, percentile 91%
public exploits
0
none known

Summary

UltraVNC revision 1198 has a heap buffer overflow vulnerability in VNC client code which results code execution. This attack appears to be exploitable via network connectivity. This vulnerability has been fixed in revision 1199.

Patch / fix

  • uvnc ultravnc 1.2.2.3
  • siemens sinumerik_access_mymachine/p2p 4.8
  • siemens sinumerik_pcu_base_win10_software/ipc 14.00

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-20-161-06 updated cvss 9.8

Siemens SINUMERIK

  • Siemens SINUMERIK Access MyMachine /P2P <V4.8
    affected: fixed in V4.8, mitigation
  • Siemens SINUMERIK PCU base Win7 software /IPC <V12.01_HF4
    affected: fixed in V12.01, mitigation
  • Siemens SINUMERIK PCU base Win10 software /IPC <V14.00
    affected: fixed in V14.00, mitigation

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

4.43% chance of exploitation in the next 30 days, higher than 91% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • UltraVNC UltraVNC

Classification

Weakness

References

Sources

Fencer Vulns 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.