Security Bulletin: Vulnerabilities in TigerVNC affect PowerKVM

Summary

PowerKVM is affected by vulnerabilities in TigerVNC. IBM has now addressed these vulnerabilities.

Vulnerability Details

CVEID: CVE-2017-7396**
DESCRIPTION:** TigerVNC is vulnerable to a denial of service, caused by a memory leak in the CConnection::CConnection function in CConnection.cxx. By sending a specially crafted request, a remote attacker could exploit this vulnerability to cause the application to stop responding.
CVSS Base Score: 7.5
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/124254 for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

CVEID: CVE-2017-7395**
DESCRIPTION:** TigerVNC is vulnerable to a denial of service, caused by an integer overflow in the SMsgReader::readClientCutText function in SMsgReader.cxx. By sending a specially crafted request, a remote authenticated attacker could exploit this vulnerability to cause the application to crash.
CVSS Base Score: 6.5
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/124253 for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)

CVEID: CVE-2017-7394**
DESCRIPTION:** TigerVNC is vulnerable to a denial of service, caused by a flaw in the SSecurityPlain::processMsg function in SSecurityPlain.cxx. By sending a specially crafted username, a remote attacker could exploit this vulnerability to cause the application to crash.
CVSS Base Score: 7.5
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/124252 for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

CVEID: CVE-2017-7393**
DESCRIPTION:** TigerVNC is vulnerable to a denial of service, caused by a double free overflow in the VNCSConnectionST::fence function in VNCSConnectionST.cxx. By sending a specially crafted request, a remote authenticated attacker could exploit this vulnerability to cause the application to crash or execute arbitrary code on the system.
CVSS Base Score: 6.3
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/124251 for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L)

CVEID: CVE-2017-7392**
DESCRIPTION:** TigerVNC is vulnerable to a denial of service, caused by a memory leak in the SSecurityVeNCrypt::SSecurityVeNCrypt function in SSecurityVeNCrypt.cxx. By sending a specially crafted request, a remote attacker could exploit this vulnerability to exhaust server memory.
CVSS Base Score: 7.5
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/124250 for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

CVEID: CVE-2017-5581**
DESCRIPTION:** TigerVNC is vulnerable to a buffer overflow, caused by improper bounds checking by the ModifiablePixelBuffer::fillRect function. By using an RRE message with subrectangle outside framebuffer boundaries, a remote attacker could overflow a buffer and execute arbitrary code on the system.
CVSS Base Score: 7.3
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/123340 for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L)

CVEID: CVE-2016-10207**
DESCRIPTION:** TigerVNC is vulnerable to a denial of service, caused by a flaw in the Xvnc server. By terminating a TLS handshake early, a remote attacker could exploit this vulnerability to cause the application to crash.
CVSS Base Score: 7.5
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/123342 for the current score
CVSS Environmental Score*: Undefined

Affected Products and Versions

PowerKVM 2.1 and 3.1

Remediation/Fixes

Customers can update PowerKVM systems by using “yum update”.

Fix images are made available via Fix Central. For version 3.1, see https://ibm.biz/BdHggw. This issue is addressed starting with v3.1.0.2 update 10.

For version 2.1, see https://ibm.biz/BdEnT8. This issue is addressed starting with PowerKVM 2.1.1.3-65 update 19. Customers running v2.1 are, in any case, encouraged to upgrade to v3.1.

For v2.1 systems currently running fix levels of PowerKVM prior to 2.1.1, please see <http://download4.boulder.ibm.com/sar/CMA/OSA/05e4c/0/README&gt; for prerequisite fixes and instructions.

Workarounds and Mitigations

none