01 事件背景

6月25日， Apache 官方安全團隊通過郵件公開報告了一個高危漏洞，郵件中介紹了 HTTP/2 拒絕服務漏洞的細節及解決方案。如下圖所示：

漏洞詳情鏈接：

• http://mail-archives.apache.org/mod_mbox/www-announce/202006.mbox/%3Cfd56bc1d-1219-605b-99c7-946bf7bd8ad4@apache.org%3E

翻譯

• 漏洞名稱：Apache Tomcat HTTP/2 拒絕服務漏洞
• 漏洞編號：CVE-2020-11996
• 嚴重程度: 重要
• 軟件提供商: Apache 軟件基金會

受影響的版本：

• Apache Tomcat 10.0.0-M1 ~ 10.0.0-M5
• Apache Tomcat 9.0.0.M1 ~ 9.0.35
• Apache Tomcat 8.5.0 ~ 8.5.55

漏洞描述：一個特別制作的 HTTP/2 請求序列，在短短數秒內能導致 CPU 滿負載率，如果有足夠數量多的此類請求連接(HTTP/2)并發放在服務器上，服務器可能會失去響應。

如果條件允許，可以通過升級到Tomcat新版本來解決漏洞。下面為受影響版本對應的安全版本：

• Apache Tomcat 10.0.0-M6+
• Apache Tomcat 9.0.36+
• Apache Tomcat 8.5.56+

02 Spring Cloud / Boot 框架影響

Apache Tomcat HTTP/2 拒絕服務漏洞也給Spring Cloud / Boot 框架帶來了一定的影響。下面是所有受影響的版本列表，大家可以查看并對照下自己的代碼，看看是否受到影響。

Spring Cloud Edgware / Spring Boot 1.5.x

• Spring Cloud [Edgware.RELEASE - Edgware.SR6] 版本受到影響。
• Spring Boot [1.5.0.RELEASE - 1.5.22.RELEASE] 版本受到影響。

Spring Cloud Finchley / Spring Boot 2.0.x

• Spring Cloud [Finchley.RELEASE - Finchley.SR4] 版本受到影響。
• Spring Boot [2.0.0.RELEASE - 2.0.9.RELEASE] 版本受到影響。

Spring Cloud Greenwich / Spring Boot 2.1.x

• Spring Cloud [Greenwich.RELEASE - Greenwich.SR6] 版本受到影響。
• Spring Boot [2.1.0.RELEASE - 2.1.14.RELEASE] 版本受到影響。
• Spring Boot [2.1.15.RELEASE] 版本已修復。

Spring Cloud Hoxton / Spring Boot 2.2.x

• Spring Cloud [Hoxton.RELEASE - Hoxton.SR6] 版本受到影響。
• Spring Boot [2.2.0.RELEASE - 2.2.7.RELEASE] 版本受到影響。
• Spring Boot [2.2.8.RELEASE] 版本已修復。

Spring Boot 2.3.x

• Spring Boot [2.3.0.RELEASE] 版本受到影響。
• Spring Boot [2.3.1.RELEASE] 版本已修復。

03 升級方案

為了避免上述漏洞，現有兩種升級方案：

直接升級Spring Boot版本。

手動升級Tomcat版本。

升級 Spring Cloud Edgware / Spring Boot 1.5.x

Edgware無法通過升級Spring Boot版本解決問題。=

<properties> 
    <tomcat-embed.version>8.5.56</tomcat-embed.version> 
</properties> 
 
<dependencyManagement> 
    <dependencies> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-core</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-el</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-websocket</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
        <dependency> 
            <groupId>org.apache.tomcat</groupId> 
            <artifactId>tomcat-annotations-api</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
    </dependencies> 
</dependencyManagement> 

升級Spring Cloud Finchley / Spring Boot 2.0.x

Finchley無法通過升級Spring Boot版本解決問題。

<properties> 
    <tomcat-embed.version>8.5.56</tomcat-embed.version> 
</properties> 
 
<dependencyManagement> 
    <dependencies> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-core</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-el</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-websocket</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
    </dependencies> 
</dependencyManagement> 

升級Spring Cloud Greenwich / Spring Boot 2.1.x

1. 升級Spring Boot

<parent> 
    <groupId>org.springframework.boot</groupId> 
    <artifactId>spring-boot-starter-parent</artifactId> 
    <version>2.1.15.RELEASE</version> 
</parent> 

2. 升級Tomcat

<properties> 
    <tomcat-embed.version>9.0.36</tomcat-embed.version> 
</properties> 
 
<dependencyManagement> 
    <dependencies> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-core</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-el</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-websocket</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
    </dependencies> 
</dependencyManagement> 

升級Spring Cloud Hoxton / Spring Boot 2.2.x

1. 升級Spring Boot

<parent> 
    <groupId>org.springframework.boot</groupId> 
    <artifactId>spring-boot-starter-parent</artifactId> 
    <version>2.2.8.RELEASE</version> 
</parent> 

2. 升級Tomcat

<properties> 
    <tomcat-embed.version>9.0.36</tomcat-embed.version> 
</properties> 
 
<dependencyManagement> 
    <dependencies> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-core</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-el</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-websocket</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
    </dependencies> 
</dependencyManagement> 

升級Spring Boot 2.3.x

1. 升級Spring Boot

<parent> 
    <groupId>org.springframework.boot</groupId> 
    <artifactId>spring-boot-starter-parent</artifactId> 
    <version>2.3.1.RELEASE</version> 
</parent> 

2. 升級Tomcat

<properties> 
    <tomcat-embed.version>9.0.36</tomcat-embed.version> 
</properties> 
 
<dependencyManagement> 
    <dependencies> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-core</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency> 
        <dependency> 
            <groupId>org.apache.tomcat.embed</groupId> 
            <artifactId>tomcat-embed-websocket</artifactId> 
            <version>${tomcat-embed.version}</version> 
        </dependency>    </dependencies></dependencyManagement>