Security Bulletin: Multiple vulnerabilities in Apache HTTP Server affect IBM i

Summary

Apache HTTP Server on IBM i is vulnerabile to the issues described in the vulnerability details section. IBM i has addressed the vulnerabilities in the Apache HTTP Server implementation as described in the remediation/fixes section.

Vulnerability Details

CVEID:CVE-2021-31618
**DESCRIPTION:**Apache HTTP Server is vulnerable to a denial of service, caused by a NULL pointer dereference in the HTTP/2 protocol handler. By sending a specially crafted HTTP/2 request, a remote attacker could exploit this vulnerability to cause a denial of service.
CVSS Base score: 5.9
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/203466 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H)

CVEID:CVE-2020-13950
**DESCRIPTION:**Apache HTTP Server is vulnerable to a denial of service, caused by a NULL pointer dereference. By sending specially crafted requests using both Content-Length and Transfer-Encoding headers, a remote attacker could exploit this vulnerability to crash mod_proxy_http.
CVSS Base score: 3.7
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/203462 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L)

CVEID:CVE-2019-17567
**DESCRIPTION:**Apache HTTP Server could allow a remote attacker to bypass security restrictions, caused by mod_proxy_wstunnel being configured on an URL that is not necessarily upgraded by the origin server. An attacker could exploit this vulnerability to allow requests on the same connection to pass through with no HTTP validation, authentication or authorization.
CVSS Base score: 5.3
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/203461 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N)

CVEID:CVE-2021-30641
**DESCRIPTION:**Apache HTTP Server could provide weaker than expected security, caused by unexpected URL matching behavior with 'MergeSlashes OFF. An attacker could exploit this vulnerability to match URLs from all sites in the same domain and launch further attacks on the system.
CVSS Base score: 5.3
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/203459 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N)

CVEID:CVE-2021-33193
**DESCRIPTION:**Apache HTTP Server is vulnerable to HTTP request splitting attacks, caused by improper input validation in HTTP/2 message processing. A remote attacker could exploit this vulnerability to inject arbitrary HTTP request and cause the browser to send 2 HTTP requests, once the URL is clicked. This would allow the attacker to perform further attacks, such as Web cache poisoning or cross-site scripting.
CVSS Base score: 6.1
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/207923 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)

Affected Products and Versions

Remediation/Fixes

The issues can be fixed by applying PTFs to the IBM i Operating System.

Releases 7.4, 7.3, and 7.2 of IBM i are supported and will be fixed.

**Release 7.4 – SI76700 and SI76706
Release 7.3 – SI76820 and SI76831
Release 7.2 – SI77099

**

Important note: IBM recommends that all users running unsupported versions of affected products upgrade to supported and fixed version of affected products.

Workarounds and Mitigations

None