uvnc vulnerabilities

Products

• UltraVNC 37
• PCHelpWareV2 2
• UltraVNC Launcher 1
• UltraVNC Viewer 1

Latest uvnc CVEs

Newest publication first · page 1 of 2

1. CVE-2026-7840 UltraVNC repeater HTTP server global buffer overflow via long URI (pre-auth RCE)

   Published 2026-07-01

   Critical·CVSS 9.3 EPSS 2.6%

   UltraVNC repeater through 1.8.2.2 contains a global buffer overflow in its embedded HTTP administration server. The functions wi_senderr() and wi_replyhdr() in repeater/webgui/webutils.c write the caller-supplied HTTP request URI into a fixed 1000-byte global buffer (hdrbuf) via...

2. CVE-2026-7839 UltraVNC repeater ships hardcoded default admin password allowing unauthenticated admin access

   Published 2026-07-01

   Critical·CVSS 9.1 EPSS 0.66%

   UltraVNC repeater through 1.8.2.2 initializes the HTTP administration server with a hardcoded default password. In repeater/webgui/settings.c:197, when settings2.txt is absent on first run the repeater writes the literal string "adminadmi2" as the admin password via strcpy_s(save...

3. CVE-2026-7838 UltraVNC viewer heap buffer overflow via integer overflow in RFB connection-failure reason length

   Published 2026-07-01

   High·CVSS 8.7 EPSS 1.9%

   UltraVNC viewer through 1.8.2.2 contains an integer overflow leading to a heap buffer overflow in the RFB protocol failure-response parsing path. In vncviewer/ClientConnection.cpp, the 4-byte network-supplied reasonLen field (type CARD32) is passed as reasonLen+1 to CheckBufferSi...

4. CVE-2026-7831 UltraVNC viewer off-by-one stack overflow in ServerInit desktop name parsing

   Published 2026-07-01

   High·CVSS 7.5 EPSS 0.74%

   UltraVNC viewer through 1.8.2.2 contains an off-by-one stack buffer overflow in the RFB ServerInit message handler. In vncviewer/ClientConnection.cpp, when the server-supplied nameLength equals exactly 2024 the code declares a 2024-byte stack buffer _dn[2024] and calls ReadString...

5. CVE-2026-7830 UltraVNC MS-Logon II uses 64-bit Diffie-Hellman and seeded libc rand() enabling credential interception

   Published 2026-07-01

   High·CVSS 7.4 EPSS 0.29%

   UltraVNC through 1.8.2.2 uses inadequate cryptography in the MS-Logon II authentication scheme (rfbUltraVNC_MsLogonIIAuth). In rfb/dh.cpp the Diffie-Hellman key exchange is performed with parameters that fit in an unsigned 64-bit integer (DH_MAX_BITS controls the prime size). A 6...

6. CVE-2026-7829 UltraVNC repeater authenticated out-of-bounds write in rule parser via oversized token

   Published 2026-07-01

   High·CVSS 7.2 EPSS 0.85%

   UltraVNC repeater through 1.8.2.2 contains a post-authentication out-of-bounds write in the allow/deny rule parser. In repeater/webgui/settings.c:225-272, after strncpy_s copies a rule token into temp1[rule1] (25-byte destination) or temp2/temp3 (16-byte destination), the code un...

7. CVE-2026-7828 UltraVNC repeater integer overflow in win_log malloc leading to heap overflow

   Published 2026-07-01

   Medium·CVSS 5.3 EPSS 1.4%

   UltraVNC repeater through 1.8.2.2 contains an integer overflow in the HTTP request logging path. In repeater/webgui/settings.c:336, the win_log() function allocates list nodes via malloc(sizeof(struct LIST) + strlen(line)), where line is derived from HTTP request URIs. If strlen(...

8. CVE-2026-44040 UltraVNC vncauth.c uses time-seeded libc rand() to generate VNC authentication challenge bytes

   Published 2026-07-01

   Medium·CVSS 6.5 EPSS 0.40%

   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 c...

9. CVE-2026-44041 UltraVNC vncWc2Mb calls wcslen() before validating that the wide string is NUL-terminated

   Published 2026-07-01

   Medium·CVSS 6.5 EPSS 0.41%

   UltraVNC through 1.8.2.2 contains an out-of-bounds read in the wide-string to multibyte conversion helper. In rfb/dh.cpp:204, the vncWc2Mb() function passes a caller-supplied WCHAR pointer to wcslen() before any bounds check. If the caller provides a wide-character buffer that is...

10. CVE-2026-44042 UltraVNC repeater wi_uudecode off-by-one in base64 decode boundary check

    Published 2026-07-01

    Low·CVSS 3.7 EPSS 0.49%

    UltraVNC repeater through 1.8.2.2 contains an off-by-one error in the Base64 decode helper used for HTTP Basic authentication. In repeater/webgui/webutils.c:817, the wi_uudecode() function checks whether the input length exceeds the output buffer with a strict greater-than compar...

11. CVE-2026-4962 UltraVNC Service version.dll uncontrolled search path

    Published 2026-03-27

    High·CVSS 7.3 EPSS 0.23%

    A security flaw has been discovered in UltraVNC up to 1.6.4.0. Affected by this issue is some unknown functionality in the library version.dll of the component Service. The manipulation results in uncontrolled search path. The attack needs to be approached locally. This attack is...

12. CVE-2019-25601 UltraVNC Launcher 1.2.2.4 Denial of Service Buffer Overflow

    Published 2026-03-22

    Medium·CVSS 6.9 EPSS 0.27%

    UltraVNC Launcher 1.2.2.4 contains a buffer overflow vulnerability in the Path vncviewer.exe property field that allows local attackers to crash the application by supplying an excessively long string. Attackers can input a 300-byte payload of repeated characters through the Prop...

13. CVE-2019-25600 UltraVNC Viewer 1.2.2.4 Denial of Service via Buffer Overflow

    Published 2026-03-22

    High·CVSS 7.1 EPSS 0.72%

    UltraVNC Viewer 1.2.2.4 contains a denial of service vulnerability that allows attackers to crash the application by supplying an oversized string to the VNC Server input field. Attackers can paste a malicious string containing 256 repeated characters into the VNC Server field an...

14. CVE-2019-25564 PCHelpWareV2 1.0.0.5 Denial of Service via Group Field

    Published 2026-03-21

    Medium·CVSS 6.8 EPSS 0.44%

    PCHelpWareV2 1.0.0.5 contains a denial of service vulnerability that allows local attackers to crash the application by supplying an excessively long string in the Group field. Attackers can paste a buffer overflow payload into the Group property field and click Ok to trigger an...

15. CVE-2019-25563 PCHelpWareV2 1.0.0.5 Denial of Service via SC Creation

    Published 2026-03-21

    Medium·CVSS 6.9 EPSS 0.19%

    PCHelpWareV2 1.0.0.5 contains a denial of service vulnerability that allows local attackers to crash the application by supplying a malformed image file. Attackers can trigger the vulnerability through the Create SC feature by selecting a crafted BMP file with an oversized buffer...

16. CVE-2026-3787 UltraVNC Windows Service cryptbase.dll uncontrolled search path

    Published 2026-03-08

    High·CVSS 7.3 EPSS 0.18%

    A weakness has been identified in UltraVNC 1.6.4.0 on Windows. This affects an unknown function in the library cryptbase.dll of the component Windows Service. This manipulation causes uncontrolled search path. The attack requires local access. A high degree of complexity is neede...

17. CVE-2020-37133 UltraVNC Launcher 1.2.4.0 - 'RepeaterHost' Denial of Service

    Published 2026-02-05

    Medium·CVSS 6.7 EPSS 0.54%

    UltraVNC Launcher 1.2.4.0 contains a denial of service vulnerability in the Repeater Host configuration field that allows attackers to crash the application. Attackers can paste an overly long string of 300 characters into the Repeater Host property to trigger an application cras...

18. CVE-2020-37132 UltraVNC Launcher 1.2.4.0 - 'Password' Denial of Service

    Published 2026-02-05

    Medium·CVSS 6.7 EPSS 0.25%

    UltraVNC Launcher 1.2.4.0 contains a denial of service vulnerability in its password configuration properties that allows local attackers to crash the application. Attackers can paste an overly long 300-character string into the password field to trigger an application crash and...

19. CVE-2022-24750 Low privilege user is able to exploit the service and gain SYSTEM privileges in UltraVNC server

    Published 2022-03-10

    High·CVSS 7.8 EPSS 0.27%

    UltraVNC is a free and open source remote pc access software. A vulnerability has been found in versions prior to 1.3.8.0 in which the DSM plugin module, which allows a local authenticated user to achieve local privilege escalation (LPE) on a vulnerable system. The vulnerability...

20. CVE-2019-8280 UltraVNC revision 1203 has out-of-bounds access vulnerability in VNC client inside RAW decoder, which can potentially result code execution. This attack appear to be exploitable via network connectivi...

    Published 2019-03-09

    Critical·CVSS 9.8 EPSS 4.2%

    UltraVNC revision 1203 has out-of-bounds access vulnerability in VNC client inside RAW decoder, which can potentially result code execution. This attack appear to be exploitable via network connectivity. This vulnerability has been fixed in revision 1204.

21. CVE-2019-8277 UltraVNC revision 1211 contains multiple memory leaks (CWE-665) in VNC server code, which allows an attacker to read stack memory and can be abused for information disclosure. Combined with another vu...

    Published 2019-03-09

    High·CVSS 7.5 EPSS 3.0%

    UltraVNC revision 1211 contains multiple memory leaks (CWE-665) in VNC server code, which allows an attacker to read stack memory and can be abused for information disclosure. Combined with another vulnerability, it can be used to leak stack memory and bypass ASLR. This attack ap...

22. CVE-2019-8276 UltraVNC revision 1211 has a stack buffer overflow vulnerability in VNC server code inside file transfer request handler, which can result in Denial of Service (DoS). This attack appears to be exploit...

    Published 2019-03-09

    High·CVSS 7.5 EPSS 5.7%

    UltraVNC revision 1211 has a stack buffer overflow vulnerability in VNC server code inside file transfer request handler, which can result in Denial of Service (DoS). This attack appears to be exploitable via network connectivity. This vulnerability has been fixed in revision 121...

23. CVE-2019-8275 UltraVNC revision 1211 has multiple improper null termination vulnerabilities in VNC server code, which result in out-of-bound data being accessed by remote users. This attack appears to be exploitabl...

    Published 2019-03-09

    Critical·CVSS 9.8 EPSS 4.0%

    UltraVNC revision 1211 has multiple improper null termination vulnerabilities in VNC server code, which result in out-of-bound data being accessed by remote users. This attack appears to be exploitable via network connectivity. These vulnerabilities have been fixed in revision 12...

24. CVE-2019-8274 UltraVNC revision 1211 has a heap buffer overflow vulnerability in VNC server code inside file transfer offer handler, which can potentially in result code execution. This attack appears to be exploit...

    Published 2019-03-09

    Critical·CVSS 9.8 EPSS 8.3%

    UltraVNC revision 1211 has a heap buffer overflow vulnerability in VNC server code inside file transfer offer handler, which can potentially in result code execution. This attack appears to be exploitable via network connectivity. This vulnerability has been fixed in revision 121...

25. CVE-2019-8273 UltraVNC revision 1211 has a heap buffer overflow vulnerability in VNC server code inside file transfer request handler, which can potentially result in code execution. This attack appears to be explo...

    Published 2019-03-09

    Critical·CVSS 9.8 EPSS 8.3%

    UltraVNC revision 1211 has a heap buffer overflow vulnerability in VNC server code inside file transfer request handler, which can potentially result in code execution. This attack appears to be exploitable via network connectivity. This vulnerability has been fixed in revision 1...

Sources: CVE.org, NVD, CISA KEV, FIRST EPSS, OSV and public exploit-reference metadata. Product matching comes from the published CVE records. A proof-of-concept means public code exists; it is not evidence of exploitation.