Summary
Package updates are available for Amazon Linux 2 that fix the following vulnerabilities: CVE-2018-5733: A denial of service flaw was found in the way dhcpd handled reference counting when processing client requests. A malicious DHCP client could use this flaw to trigger a reference count overflow on the server side, potentially causing dhcpd to crash, by sending large amounts of traffic. 1549961: CVE-2018-5733 dhcp: Reference count overflow in dhcpd allows denial of service CVE-2018-5732: An out-of-bound memory access flaw was found in the way dhclient processed a DHCP response packet. A malicious DHCP server could potentially use this flaw to crash dhclient processes running on DHCP client machines via a crafted DHCP response packet. 1549960: CVE-2018-5732 dhcp: Buffer overflow in dhclient possibly allowing code execution triggered by malicious server
Fixed packages 6
| Release | Package | Fixed in |
|---|---|---|
| Amazon Linux · 2 | dhclient | 12:4.2.5-58.amzn2.3.2 |
| Amazon Linux · 2 | dhcp | 12:4.2.5-58.amzn2.3.2 |
| Amazon Linux · 2 | dhcp-common | 12:4.2.5-58.amzn2.3.2 |
| Amazon Linux · 2 | dhcp-debuginfo | 12:4.2.5-58.amzn2.3.2 |
| Amazon Linux · 2 | dhcp-devel | 12:4.2.5-58.amzn2.3.2 |
| Amazon Linux · 2 | dhcp-libs | 12:4.2.5-58.amzn2.3.2 |
Vulnerabilities 2
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High 7.5
A specially constructed response from a malicious server can cause a buffer overflow in dhclient
Failure to properly bounds-check a buffer used for processing DHCP options allows a malicious server (or an entity masquerading as a server) to cause a buffer overflow (and resulting crash) in dhclient by sending a response containing a specially constructed …
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Medium 5.9CVE-2018-5733 EPSS 20%
A malicious client can overflow a reference counter in ISC dhcpd
A malicious client which is allowed to send very large amounts of traffic (billions of packets) to a DHCP server can eventually overflow a 32-bit reference counter, potentially causing dhcpd to crash. Affects ISC DHCP 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3…