Multiple vulnerabilities in Apache HTTP Server
| Risk | Critical |
| Patch available | YES |
| Number of vulnerabilities | 2 |
| CVE-ID | CVE-2021-41773 CVE-2021-41524 |
| CWE-ID | CWE-22 CWE-476 |
| Exploitation vector | Network |
| Public exploit | Vulnerability #1 is being exploited in the wild. |
| Vulnerable software |
Apache HTTP Server Server applications / Web servers |
| Vendor | Apache Foundation |
Security Bulletin
This security bulletin contains information about 2 vulnerabilities.
Updated: 07.10.2021
Updated vulnerability description and CVSS score to reflect remote command execution for vulnerability #VU57063, raised bulletin severity level from High to Critical.
1) Path traversal
EUVDB-ID: #VU57063
Risk: Critical
CVSSv3.1: 9.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C]
CVE-ID: CVE-2021-41773
CWE-ID:
CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Exploit availability: Yes
DescriptionThe vulnerability allows a remote attacker to perform directory traversal attacks.
The vulnerability exists due to input validation error when processing directory traversal sequences. A remote attacker can send a specially crafted HTTP request to map URLs to files outside the expected document root. If files outside of the document root are not protected by "require all denied" these requests can succeed. Additionally this flaw could leak the source of interpreted files like CGI scripts.
The vulnerability can be used to execute arbitrary OS commands on the system.
Note, the vulnerability is being actively exploited in the wild.
Install update from vendor's website.
Vulnerable software versionsApache HTTP Server: 2.4.49
CPE2.3 External linkshttp://httpd.apache.org/security/vulnerabilities_24.html
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
How the attacker can exploit this vulnerability?
The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.
Is there known malware, which exploits this vulnerability?
Yes. This vulnerability is being exploited in the wild.
2) NULL pointer dereference
EUVDB-ID: #VU57062
Risk: Medium
CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2021-41524
CWE-ID:
CWE-476 - NULL Pointer Dereference
Exploit availability: No
DescriptionThe vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to a NULL pointer dereference error when processing HTTP/2 requests. A remote attacker can send a specially crafted HTTP/2 request to the affected Apache HTTP server and perform a denial of service (DoS) attack.
MitigationInstall update from vendor's website.
Vulnerable software versionsApache HTTP Server: 2.4.49
CPE2.3 External linkshttp://httpd.apache.org/security/vulnerabilities_24.html
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
How the attacker can exploit this vulnerability?
The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
