Medium: tigervnc

Issue Overview:

TigerVNC version prior to 1.10.1 is vulnerable to stack use-after-return, which occurs due to incorrect usage of stack memory in ZRLEDecoder. If decoding routine would throw an exception, ZRLEDecoder may try to access stack variable, which has been already freed during the process of stack unwinding. Exploitation of this vulnerability could potentially result into remote code execution. This attack appear to be exploitable via network connectivity. (CVE-2019-15691)

TigerVNC version prior to 1.10.1 is vulnerable to heap buffer overflow. Vulnerability could be triggered from CopyRectDecoder due to incorrect value checks. Exploitation of this vulnerability could potentially result into remote code execution. This attack appear to be exploitable via network connectivity. (CVE-2019-15692)

TigerVNC version prior to 1.10.1 is vulnerable to heap buffer overflow, which occurs in TightDecoder::FilterGradient. Exploitation of this vulnerability could potentially result into remote code execution. This attack appear to be exploitable via network connectivity. (CVE-2019-15693)

TigerVNC version prior to 1.10.1 is vulnerable to heap buffer overflow, which could be triggered from DecodeManager::decodeRect. Vulnerability occurs due to the signdness error in processing MemOutStream. Exploitation of this vulnerability could potentially result into remote code execution. This attack appear to be exploitable via network connectivity. (CVE-2019-15694)

TigerVNC version prior to 1.10.1 is vulnerable to stack buffer overflow, which could be triggered from CMsgReader::readSetCursor. This vulnerability occurs due to insufficient sanitization of PixelFormat. Since remote attacker can choose offset from start of the buffer to start writing his values, exploitation of this vulnerability could potentially result into remote code execution. This attack appear to be exploitable via network connectivity. (CVE-2019-15695)

Affected Packages:

tigervnc

Issue Correction:
Run yum update tigervnc to update your system.

New Packages:

i686:  
    tigervnc-debuginfo-1.8.0-21.34.amzn1.i686  
    tigervnc-1.8.0-21.34.amzn1.i686  
    tigervnc-server-module-1.8.0-21.34.amzn1.i686  
    tigervnc-server-1.8.0-21.34.amzn1.i686  
  
src:  
    tigervnc-1.8.0-21.34.amzn1.src  
  
x86_64:  
    tigervnc-1.8.0-21.34.amzn1.x86_64  
    tigervnc-server-module-1.8.0-21.34.amzn1.x86_64  
    tigervnc-debuginfo-1.8.0-21.34.amzn1.x86_64  
    tigervnc-server-1.8.0-21.34.amzn1.x86_64  

Additional References

Red Hat: CVE-2019-15691, CVE-2019-15692, CVE-2019-15693, CVE-2019-15694, CVE-2019-15695

Mitre: CVE-2019-15691, CVE-2019-15692, CVE-2019-15693, CVE-2019-15694, CVE-2019-15695