Multiple vulnerabilities in Apache HTTP Server

1) NULL pointer dereference

EUVDB-ID: #VU53773

Risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-31618

CWE-ID: CWE-476 - NULL Pointer Dereference

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in mod_http2 in Apache HTTP server. A remote attacker can send specially crafted request to the server and perform a denial of service (DoS) attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Apache HTTP Server: 2.4 - 2.4.47

CPE2.3

External links

https://downloads.apache.org/httpd/CHANGES_2.4.48

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.

2) Input validation error

EUVDB-ID: #VU53774

Risk: Medium

CVSSv4.0: 6.9 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-30641

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to incorrect parsing of Apache configuration files. An unexpected section could be matched with 'MergeSlashes OFF' option, leading to a potential security issue.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Apache HTTP Server: 2.4 - 2.4.46

CPE2.3

External links

https://downloads.apache.org/httpd/CHANGES_2.4.48

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.

3) Stack-based buffer overflow

EUVDB-ID: #VU53775

Risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-35452

CWE-ID: CWE-121 - Stack-based buffer overflow

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a boundary error when processing Digest nounces in mod_auth_digest. A remote unauthenticated attacker can send a specially crafted HTTP request, trigger stack overflow by one nul byte and crash the server.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Apache HTTP Server: 2.4 - 2.4.46

CPE2.3

External links

https://downloads.apache.org/httpd/CHANGES_2.4.48

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.

4) NULL pointer dereference

EUVDB-ID: #VU53776

Risk: Low

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-26691

CWE-ID: CWE-476 - NULL Pointer Dereference

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in mod_session. A a malicious backend server or SessionHeader can trigger a denial of service (DoS) condition.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Apache HTTP Server: 2.4 - 2.4.46

CPE2.3

External links

https://downloads.apache.org/httpd/CHANGES_2.4.48

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.

5) NULL pointer dereference

EUVDB-ID: #VU53777

Risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-26690

CWE-ID: CWE-476 - NULL Pointer Dereference

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in mod_session. A remote attacker can pass specially crafted data to the application and perform a denial of service (DoS) attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Apache HTTP Server: 2.4 - 2.4.46

CPE2.3

External links

https://downloads.apache.org/httpd/CHANGES_2.4.48

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.

6) NULL pointer dereference

EUVDB-ID: #VU53778

Risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-13950

CWE-ID: CWE-476 - NULL Pointer Dereference

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in mod_proxy_http. A remote attacker can pass specially crafted data to the application and perform a denial of service (DoS) attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Apache HTTP Server: 2.4 - 2.4.46

CPE2.3

External links

https://downloads.apache.org/httpd/CHANGES_2.4.48

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.

7) Improper Privilege Management

EUVDB-ID: #VU53779

Risk: Low

CVSSv4.0: 4.3 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2020-13938

CWE-ID: CWE-269 - Improper Privilege Management

Exploit availability: No

Description

The vulnerability allows a local user to stop the service.

The vulnerability exists due to improper privilege management. A local user can on the Windows system can stop the Apache HTTP server service.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Apache HTTP Server: 2.4 - 2.4.46

CPE2.3

External links

https://downloads.apache.org/httpd/CHANGES_2.4.48

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

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.

The attacker would have to login to the system and perform certain actions in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

8) Security restrictions bypass

EUVDB-ID: #VU53780

Risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-17567

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to unspecified error within the mod_proxy_wstunnel and mod_proxy_http modules. If mod_proxy_wstunnel is configured on an URL that is not necessarily Upgraded by the origin server and is tunneling the whole connection regardless, thus allowing for subsequent requests on the same connection to pass through with no HTTP validation, authentication or authorization possibly configured.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Apache HTTP Server: 2.4 - 2.4.46

CPE2.3

External links

https://downloads.apache.org/httpd/CHANGES_2.4.48

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the local network (LAN).

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.

Risk	Medium
Patch available	YES
Number of vulnerabilities	8
CVE-ID	CVE-2021-31618 CVE-2021-30641 CVE-2020-35452 CVE-2021-26691 CVE-2021-26690 CVE-2020-13950 CVE-2020-13938 CVE-2019-17567
CWE-ID	CWE-476 CWE-20 CWE-121 CWE-269 CWE-264
Exploitation vector	Network
Public exploit	N/A
Vulnerable software	Apache HTTP Server Server applications / Web servers
Vendor	Apache Foundation