CVE-2021-23017

一、漏洞信息
 漏洞编号：[CVE-2021-23017](https://nvd.nist.gov/vuln/detail/CVE-2021-23017)
 漏洞归属组件：[nginx](https://gitee.com/src-openeuler/nginx)
 漏洞归属的版本：1.16.1,1.18.0,1.19.1
 CVSS V3.0分值：
  BaseScore：9.8 Critical
  Vector：CVSS：3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
 漏洞简述：
  A security issue in nginx resolver was identified, which might allow an attacker who is able to forge UDP packets from the DNS server to cause 1-byte memory overwrite, resulting in worker process crash or potential other impact.
 漏洞公开时间：2021-06-01 21:15
 漏洞创建时间：2021-06-11 11:55:05
 漏洞详情参考链接：
  https://nvd.nist.gov/vuln/detail/CVE-2021-23017
<details>
<summary>更多参考(点击展开)</summary>

| 参考来源 | 参考链接 | 来源链接 |
| ------- | -------- | -------- |
| MISC | http://mailman.nginx.org/pipermail/nginx-announce/2021/000300.html |  |
| MISC | https://support.f5.com/csp/article/K12331123, |  |
| MLIST | https://lists.apache.org/thread.html/r6fc5c57b38e93e36213e9a18c8a4e5dbd5ced1c7e57f08a1735975ba@%3Cnotifications.apisix.apache.org%3E |  |
| MLIST | https://lists.apache.org/thread.html/rf318aeeb4d7a3a312734780b47de83cefb7e6995da0b2cae5c28675c@%3Cnotifications.apisix.apache.org%3E |  |
| MLIST | https://lists.apache.org/thread.html/r37e6b2165f7c910d8e15fd54f4697857619ad2625f56583802004009@%3Cnotifications.apisix.apache.org%3E |  |
| MLIST | https://lists.apache.org/thread.html/rf232eecd47fdc44520192810560303073cefd684b321f85e311bad31@%3Cnotifications.apisix.apache.org%3E |  |
| MLIST | https://lists.apache.org/thread.html/r4d4966221ca399ce948ef34884652265729d7d9ef8179c78d7f17e7f@%3Cnotifications.apisix.apache.org%3E |  |
| FEDORA | https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/7SFVYHC7OXTEO4SMBWXDVK6E5IMEYMEE/ |  |
| FEDORA | https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/GNKOP2JR5L7KCIZTJRZDCUPJTUONMC5I/ |  |
| CONFIRM | https://security.netapp.com/advisory/ntap-20210708-0006/ |  |
| MISC | https://www.oracle.com/security-alerts/cpuoct2021.html |  |
| MISC | https://www.oracle.com/security-alerts/cpujan2022.html |  |
| MISC | https://www.oracle.com/security-alerts/cpuapr2022.html |  |
| nvd | https://access.redhat.com/security/cve/CVE-2021-23017 |  |
| suse_bugzilla | https://nginx.org/keys/maxim.key

==Timeline==

A remote heap corruption in nginx was reported to the nginx maintainers
on April 30th. As they already hinted they might not have a release
in time for the disclosure date, we are notifying distros@ including a
workaround patch that is not an official vendor patch.

In line with the distros@ disclosure policy, we ask for the maximum
embargo time of 14 days and would like to disclosure this vulnerability
on May 31st, 11:00am CEST.

==Description==

An off-by-one error in ngx_resolver_copy( |  |
| suse_bugzilla | http{
    access_log logs/access.log;
    server{
        listen 8080;
        location / {
            resolver 127.0.0.1:1053;
            set $dns http://example.net;
            proxy_pass $dns;
        }
    }
}

events {
    worker_connections  1024;
}

-----------------

$ valgrind --trace-children=yes nginx -p runtime -c reverse-proxy.conf
$ python dns.py # listens on 1053 udp
$ curl http://127.0.0.1:8080/

Depending on the heap layout when the bug triggers, the malloc
mitigations might detect or not the effect. Several ways of showing up
in the logs arise:

</details>

漏洞分析指导链接：
  https://gitee.com/openeuler/cve-manager/blob/master/cve-vulner-manager/doc/md/manual.md
 漏洞数据来源:
  其它
 漏洞补丁信息：
  <details>
<summary>详情(点击展开)</summary>

无
</details>

二、漏洞分析结构反馈
 影响性分析说明：
    在 nginx 中发现了一个缺陷。处理 DNS 响应时的一个差错允许网络攻击者在堆分配的缓冲区中写入越界的点字符，这可能允许覆盖下一个堆块元数据的最低有效字节，这可能导致在某些情况下远程执行代码情况。此漏洞的最大威胁是数据机密性和完整性以及系统可用性。 
 openEuler评分：
  9.8
 Vector：CVSS：3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
 受影响版本排查(受影响/不受影响)：
  1.openEuler-20.03-LTS(1.16.1):受影响
2.openEuler-20.03-LTS-Next(1.16.1):受影响
3.openEuler-20.03-LTS-SP1(1.21.5):受影响
4.openEuler-20.03-LTS-SP2(1.21.5):受影响
5.master(1.23.2):受影响

修复是否涉及abi变化(是/否)：
  1.openEuler-20.03-LTS(1.16.1):否
2.openEuler-20.03-LTS-SP1(1.21.5):否
3.openEuler-20.03-LTS-Next(1.16.1):否
4.openEuler-20.03-LTS-SP2(1.21.5):否
5.master(1.23.2):否

三、漏洞修复
安全公告链接：https://www.openeuler.org/zh/security/safety-bulletin/detail/?id=openEuler-SA-2021-1225

CVE-2021-23017
影响性分析说明：在 nginx 中发现了一个缺陷。处理 DNS 响应时的一个差错允许网络攻击者在堆分配的缓冲区中写入越界的点字符，这可能允许覆盖下一个堆块元数据的最低有效字节，这可能导致在某些情况下远程执行代码情况。此漏洞的最大威胁是数据机密性和完整性以及系统可用性。
openEuler评分: 9.8(3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)

受影响版本排查(受影响/不受影响):
1.openEuler-20.03-LTS:受影响
2.openEuler-20.03-LTS-Next:受影响
3.openEuler-20.03-LTS-SP1:受影响
4.openEuler-20.03-LTS-SP2:受影响
5.master:受影响

是否涉及abi变化(是/否)：
1.openEuler-20.03-LTS:否
2.openEuler-20.03-LTS-SP1:否
3.openEuler-20.03-LTS-Next:否
4.openEuler-20.03-LTS-SP2:否
5.master:否

CVE-2021-23017
影响性分析说明：在 nginx 中发现了一个缺陷。处理 DNS 响应时的一个差错允许网络攻击者在堆分配的缓冲区中写入越界的点字符，这可能允许覆盖下一个堆块元数据的最低有效字节，这可能导致在某些情况下远程执行代码情况。此漏洞的最大威胁是数据机密性和完整性以及系统可用性。
openEuler评分: 9.8(3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)

受影响版本排查(受影响/不受影响):
1.openEuler-20.03-LTS:受影响
2.openEuler-20.03-LTS-Next:受影响
3.openEuler-20.03-LTS-SP1:受影响
4.openEuler-20.03-LTS-SP2:受影响
5.master:受影响

修复是否涉及abi变化(是/否)：
1.openEuler-20.03-LTS:否
2.openEuler-20.03-LTS-SP1:否
3.openEuler-20.03-LTS-Next:否
4.openEuler-20.03-LTS-SP2:否
5.master:否

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