Two heap-based buffer overflows in LibVNCClient
| Risk | Medium |
| Patch available | YES |
| Number of vulnerabilities | 2 |
| CVE-ID | CVE-2016-9942 CVE-2016-9941 |
| CWE-ID | CWE-119 |
| Exploitation vector | Network |
| Public exploit | N/A |
| Vulnerable software Subscribe |
LibVNCServer Server applications / Remote management servers, RDP, SSH |
| Vendor | LibVNC |
Security Bulletin
This security bulletin contains information about 2 vulnerabilities.
1) Heap-based buffer overflow
EUVDB-ID: #VU3077
Risk: Medium
CVSSv3.1: 7.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2016-9942
CWE-ID:
CWE-119 - Memory corruption
Exploit availability: No
DescriptionThe vulnerability allows a remote attacker to execute arbitrary code on vulnerable client system.
A heap-based buffer overflow vulnerability exists due to boundary error in ultra.c in LibVNCClient software, which is bundled with LibVNCServer. A remote attacker can trick the victim to connect to malicious VNC server, send a specially crafted FramebufferUpdate message with the Ultra type tile, such that the LZO payload decompressed length exceeds what is specified by the tile dimensions, and trigger buffer overflow.
Successful exploitation of the vulnerability may allow an attacker to execute arbitrary code on vulnerable VNC client.
Update to version 0.9.11:
https://github.com/LibVNC/libvncserver/tree/LibVNCServer-0.9.11
LibVNCServer: 0.9.9 - 0.9.10
External linkshttp://github.com/LibVNC/libvncserver/pull/137
http://github.com/LibVNC/libvncserver/releases/tag/LibVNCServer-0.9.11
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
How the attacker can exploit this vulnerability?
The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
2) Heap-based buffer overflow
EUVDB-ID: #VU3076
Risk: Medium
CVSSv3.1: 7.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2016-9941
CWE-ID:
CWE-119 - Memory corruption
Exploit availability: No
DescriptionThe vulnerability allows a remote attacker to execute arbitrary code on vulnerable client system.
A heap-based buffer overflow vulnerability exists due to boundary error in rfbproto.c in LibVNCClient software, which is bundled with LibVNCServer. A remote attacker can trick the victim to connect to malicious VNC server, send a specially crafted FramebufferUpdate message containing a subrectangle outside of the client drawing area and trigger buffer overflow.
Successful exploitation of the vulnerability may allow an attacker to execute arbitrary code on vulnerable VNC client.
Update to version 0.9.11:
https://github.com/LibVNC/libvncserver/tree/LibVNCServer-0.9.11
LibVNCServer: 0.9.9 - 0.9.10
External linkshttp://github.com/LibVNC/libvncserver/pull/137
http://github.com/LibVNC/libvncserver/releases/tag/LibVNCServer-0.9.11
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
How the attacker can exploit this vulnerability?
The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
