New upstream release. Contains security fix for CVE-2016-2774.

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

From Red Hat Security Advisory 2016:2590 :

An update for dhcp is now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having a security impact of Moderate. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

The Dynamic Host Configuration Protocol (DHCP) is a protocol that allows individual devices on an IP network to get their own network configuration information, including an IP address, a subnet mask, and a broadcast address. The dhcp packages provide a relay agent and ISC DHCP service required to enable and administer DHCP on a network.

Security Fix(es) :

* A resource-consumption flaw was discovered in the DHCP server. dhcpd did not restrict the number of open connections to OMAPI and failover ports. A remote attacker able to establish TCP connections to one of these ports could use this flaw to cause dhcpd to exit unexpectedly, stop responding requests, or exhaust system sockets (denial of service). (CVE-2016-2774)

Red Hat would like to thank ISC for reporting this issue.

Additional Changes :

For detailed information on changes in this release, see the Red Hat Enterprise Linux 7.3 Release Notes linked from the References section.

RedHat Enterprise Linux 6 / 7 受隨附 ISC DHCP 伺服器中的拒絕服務弱點影響，這是因為無法將並行 TCP 工作階段數正確限制為伺服器針對處理程序間通訊與控制使用的連接埠。未經驗證的遠端攻擊者可惡意利用此弱點，透過開啟大量的 TCP 工作階段，造成伺服器無法處理要求或意外結束，或造成耗盡系統通訊端。

請注意，當 DHCP 伺服器將 OMAPI 用於遠端管理時，此弱點更容易遭到惡意利用。

此 dhcp 更新可修正下列問題：

- CVE-2016-2774：修正透過 OMAPI TCP 通訊端對 DHCP 伺服器發動的拒絕服務攻擊，網路相鄰攻擊者原本可利用該弱點使 DHCP 伺服器失去運作功能 (bsc#969820)。

請注意，Tenable Network Security 已直接從 SUSE 安全性公告擷取前置描述區塊。Tenable 已盡量在不造成其他問題的前提下，嘗試自動清理並將其格式化。

此 dhcp 更新可修正下列問題：

修正的安全性問題：

- CVE-2016-2774：修正透過 OMAPI TCP 通訊端對 DHCP 伺服器發動的拒絕服務攻擊，網路相鄰攻擊者原本可利用該弱點使 DHCP 伺服器失去運作功能 (bsc#969820)。

已修正的非安全性問題：

- 重新命名未考慮 /etc/hosts 和 /etc/nsswitch.conf 之內部 libirs 程式庫的 freeaddrinfo()、getaddrinfo() 和 getnameinfo()，以使用 irs_ prefix。
 此可避免名稱衝突，該衝突會導致覆寫 libldap 所使用的標準 glibc 函式。
 (bsc#972907)

此更新是從 SUSE:SLE-12-SP1:Update 更新專案匯入。

RedHat Enterprise Linux 6 / 7 受到捆绑 ISC DHCP 服务器中拒绝服务漏洞的影响，这是因为无法将并发 TCP 会话数正确限制为服务器针对进程间通信与控制使用的端口。未经认证的远程攻击者可利用此漏洞，通过开启大量的 TCP 会话，造成服务器无法处理请求或意外退出，或造成耗尽系统套接字。

请注意，当 DHCP 服务器将 OMAPI 用于远程管理时，此漏洞更容易遭到利用。

此 dhcp 更新可修复下列问题：

- CVE-2016-2774：已修复通过 OMAPI TCP 套接字对 DHCP 服务器发动的拒绝服务攻击，该漏洞可被网络邻近利用，造成 DHCP 服务器无法工作 (bsc#969820)。

请注意，Tenable Network Security 已直接从 SUSE 安全公告中提取上述描述块。Tenable 已尝试在不引入其他问题的情况下尽可能进行了自动整理和排版。

此 dhcp 更新可修复下列问题：

修复的安全问题：

- CVE-2016-2774：已修复通过 OMAPI TCP 套接字对 DHCP 服务器发动的拒绝服务攻击，该漏洞可被网络邻近利用，造成 DHCP 服务器无法工作 (bsc#969820)。

已修复的非安全问题：

- 重命名未考虑 /etc/hosts 和 /etc/nsswitch.conf 的内部 libirs 库中的 freeaddrinfo()、getaddrinfo() 和 getnameinfo()，以使用 irs_ prefix。
 此可避免名称冲突，该冲突可能导致覆盖 libldap 所使用的标准 glibc 函数。
 (bsc#972907)

此更新从 SUSE:SLE-12-SP1:Update 更新项目导入。

According to the versions of the dhcp packages installed, the EulerOS Virtualization installation on the remote host is affected by the following vulnerabilities :

  - ISC DHCP 4.x before 4.1-ESV-R12-P1, 4.2.x, and 4.3.x     before 4.3.3-P1 allows remote attackers to cause a     denial of service (application crash) via an invalid     length field in a UDP IPv4 packet.(CVE-2015-8605)

  - 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.(CVE-2018-5733)

  - 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.(CVE-2018-5732)

  - A resource-consumption flaw was discovered in the DHCP     server. dhcpd did not restrict the number of open     connections to OMAPI and failover ports. A remote     attacker able to establish TCP connections to one of     these ports could use this flaw to cause dhcpd to exit     unexpectedly, stop responding requests, or exhaust     system sockets (denial of service).(CVE-2016-2774)

  - It was found that the DHCP daemon did not properly     clean up closed OMAPI connections in certain cases. A     remote attacker able to connect to the OMAPI port could     use this flaw to exhaust file descriptors in the DHCP     daemon, leading to a denial of service in the OMAPI     functionality.(CVE-2017-3144)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

This update for dhcp fixes the following issues :

Security issue fixed :

  - CVE-2016-2774: Fixed a denial of service attack against     the DHCP server over the OMAPI TCP socket, which could     be used by network adjacent attackers to make the DHCP     server non-functional (bsc#969820).

Non security issues fixed :

  - Rename freeaddrinfo(), getaddrinfo() and getnameinfo()     in the internal libirs library that does not consider     /etc/hosts and /etc/nsswitch.conf to use irs_ prefix.
    This prevents name conflicts which would result in     overriding standard glibc functions used by libldap.
    (bsc#972907)

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Security fix for CVE-2016-2774

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote Redhat Enterprise Linux 5 host has one or more packages installed that are affected by multiple vulnerabilities that have been acknowledged by the vendor but will not be patched.

  - dhcp: unclosed TCP connections to OMAPI or failover ports can cause DoS (CVE-2016-2774)

  - dhcp: Reference count overflow in dhcpd allows denial of service (CVE-2018-5733)

  - ISC DHCP 4.x before 4.1-ESV-R12-P1, 4.2.x, and 4.3.x before 4.3.3-P1 allows remote attackers to cause a     denial of service (application crash) via an invalid length field in a UDP IPv4 packet. (CVE-2015-8605)

Note that Nessus has not tested for these issues but has instead relied on the package manager's report that the package is installed.

The remote Redhat Enterprise Linux 6 host has one or more packages installed that are affected by multiple vulnerabilities that have been acknowledged by the vendor but will not be patched.

  - dhcp: UDP payload length not properly checked (CVE-2015-8605)

  - dhcp: unclosed TCP connections to OMAPI or failover ports can cause DoS (CVE-2016-2774)

Note that Nessus has not tested for these issues but has instead relied on the package manager's report that the package is installed.

ID	名稱	產品	系列	已發布	已更新	嚴重性
90962	Fedora 24 : dhcp-4.3.4-1.fc24 (2016-821f013cb1)	Nessus	Fedora Local Security Checks	2016/5/9	2021/1/11	medium
94711	Oracle Linux 7 : dhcp (ELSA-2016-2590)	Nessus	Oracle Linux Local Security Checks	2016/11/11	2021/1/14	medium
90250	RHEL 6 / 7：ISC DHCP 並行 TCP 工作階段 DoS	Nessus	Red Hat Local Security Checks	2016/3/29	2018/7/27	high
93167	SUSE SLED12 / SLES12 安全性更新：dhcp (SUSE-SU-2016:1692-1)	Nessus	SuSE Local Security Checks	2016/8/29	2021/1/6	medium
93286	SUSE SLES11 安全性更新：dhcp (SUSE-SU-2016:2024-1)	Nessus	SuSE Local Security Checks	2016/9/2	2021/1/19	medium
92506	openSUSE 安全性更新：dhcp (openSUSE-2016-887)	Nessus	SuSE Local Security Checks	2016/7/22	2021/1/19	medium
90250	RHEL 6 / 7：ISC DHCP 并发 TCP 会话 DoS	Nessus	Red Hat Local Security Checks	2016/3/29	2018/7/27	high
93167	SUSE SLED12 / SLES12 安全更新：dhcp (SUSE-SU-2016:1692-1)	Nessus	SuSE Local Security Checks	2016/8/29	2021/1/6	medium
93286	SUSE SLES11 安全更新：dhcp (SUSE-SU-2016:2024-1)	Nessus	SuSE Local Security Checks	2016/9/2	2021/1/19	medium
92506	openSUSE 安全更新：dhcp (openSUSE-2016-887)	Nessus	SuSE Local Security Checks	2016/7/22	2021/1/19	medium
124946	EulerOS Virtualization 3.0.1.0 : dhcp (EulerOS-SA-2019-1443)	Nessus	Huawei Local Security Checks	2019/5/14	2022/5/20	high
93181	SUSE SLED12 / SLES12 Security Update : dhcp (SUSE-SU-2016:1791-1)	Nessus	SuSE Local Security Checks	2016/8/29	2021/1/6	medium
92086	Fedora 22 : 12:dhcp (2016-3e64b32a91)	Nessus	Fedora Local Security Checks	2016/7/14	2021/1/11	medium
199428	RHEL 5 : dhcp (Unpatched Vulnerability)	Nessus	Red Hat Local Security Checks	2024/6/3	2024/6/3	high
199472	RHEL 6 : dhcp (Unpatched Vulnerability)	Nessus	Red Hat Local Security Checks	2024/6/3	2024/6/3	medium

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