Security Bulletin: IBM HTTP Server (powered by Apache) for IBM i is vulnerable to a denial of service attack using HTTP/2 protocol. [CVE-2023-44487]

Summary

IBM HTTP Server (powered by Apache) used by IBM i is vulnerable to a denial of service attack due to mishandling of multiplexed streams in HTTP/2 protocol as described in the vulnerability details section. This bulletin identifies the steps to take to address the vulnerability as described in the remediation/fixes section.

Vulnerability Details

CVEID:CVE-2023-44487
**DESCRIPTION:**Multiple vendors are vulnerable to a denial of service, caused by a flaw in handling multiplexed streams in the HTTP/2 protocol. By sending numerous HTTP/2 requests and RST_STREAM frames over multiple streams, a remote attacker could exploit this vulnerability to cause a denial of service due to server resource consumption.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/268044 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Affected Products and Versions

Remediation/Fixes

The issue can be addressed by applying a PTF to IBM i. IBM i releases 7.5, 7.4, and 7.3 will be fixed.

The IBM i PTF number for 5770-DG1 contains the fix to resolve the vulnerability.

IBM i Release| 5770-DG1
PTF Number| PTF Download Link
—|—|—
7.5| SJ00522| <https://www.ibm.com/mysupport/s/fix-information/aDrKe0000004D60KAE&gt;
7.4| SJ00521| <https://www.ibm.com/mysupport/s/fix-information/aDrKe0000004D5vKAE&gt;
7.3| SJ00520| <https://www.ibm.com/mysupport/s/fix-information/aDrKe0000004D5qKAE&gt;

https://www.ibm.com/support/fixcentral

_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.