Security Bulletin
Summary
IBM HTTP Server used by IBM WebSphere Application Server is affected by multiple vulnerabilities due to libexpat and the included Apache HTTP Server.
Vulnerability Details
CVEID: CVE-2026-24072
DESCRIPTION: An escalation of privilege bug in various modules in Apache HTTP 2.4.66 and earlier allows local .htaccess authors to read files with the privileges of the httpd user.
Users are recommended to upgrade to version 2.4.67, which fixes this issue.
CWE: CWE-269: Improper Privilege Management
CVSS Source: CISA ADP
CVSS Base score: 8.8
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
CVEID: CVE-2026-28780
DESCRIPTION: Heap-based Buffer Overflow vulnerability in mod_proxy_ajp of Apache HTTP Server.
If mod_proxy_ajp connects to a malicious AJP server this AJP server can send a malicious AJP message back to mod_proxy_ajp and cause it to write 4 attacker controlled bytes after the end of a heap based buffer.
This issue affects Apache HTTP Server: through 2.4.66.
Users are recommended to upgrade to version 2.4.67, which fixes the issue.
CWE: CWE-122: Heap-based Buffer Overflow
CVSS Source: CISA ADP
CVSS Base score: 9.8
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
CVEID: CVE-2026-34059
DESCRIPTION: Buffer Over-read vulnerability in Apache HTTP Server.
This issue affects Apache HTTP Server: through 2.4.66.
Users are recommended to upgrade to version 2.4.67, which fixes the issue.
CWE: CWE-126: Buffer Over-read
CVSS Source: CISA ADP
CVSS Base score: 7.5
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)
CVEID: CVE-2026-33523
DESCRIPTION: HTTP response splitting vulnerability in multiple Apache HTTP Server modules with untrusted or compromised backend servers.
This issue affects Apache HTTP Server: from through 2.4.66.
Users are recommended to upgrade to version 2.4.67, which fixes the issue.
CWE: CWE-443: DEPRECATED: HTTP response splitting
CVSS Source: CISA ADP
CVSS Base score: 6.5
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N)
CVEID: CVE-2026-41080
DESCRIPTION: libexpat before 2.8.0 uses insufficient entropy, and thus hash flooding can occur via a crafted XML document.
CWE: CWE-331: Insufficient Entropy
CVSS Source: cve@mitre.org
CVSS Base score: 2.9
CVSS Vector: (CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L)
CVEID: CVE-2026-33857
DESCRIPTION: Out-of-bounds Read vulnerability in mod_proxy_ajp of
Apache HTTP Server.
This issue affects Apache HTTP Server: through 2.4.66.
Users are recommended to upgrade to version 2.4.67, which fixes the issue.
CWE: CWE-125: Out-of-bounds Read
CVSS Source: CISA ADP
CVSS Base score: 5.3
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)
CVEID: CVE-2026-34032
DESCRIPTION: Improper Null Termination, Out-of-bounds Read vulnerability in Apache HTTP Server.
This issue affects Apache HTTP Server: through 2.4.66.
Users are recommended to upgrade to version 2.4.67, which fixes the issue.
CWE: CWE-125: Out-of-bounds Read
CVSS Source: CISA ADP
CVSS Base score: 5.3
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)
Affected Products and Versions
The vulnerabilities affect the following version and release of IBM HTTP Server (powered by Apache) component in all editions of IBM WebSphere Application Server and bundling products.
| Affected Product(s) | Version(s) |
| IBM HTTP Server | 8.5 |
| IBM HTTP Server | 9.0 |
Remediation/Fixes
IBM strongly recommends addressing the vulnerability now by applying a currently available interim fix or fix pack that contains the fix for APAR PH71061.
For IBM HTTP Server used by IBM WebSphere Application Server:
For V9.0.0.0 through 9.0.5.27:
· Upgrade to minimal fix pack levels as required by the interim fix and then apply the Interim Fix that resolves PH71061
--OR--
· Apply Fix Pack 9.0.5.28 or later (targeted availability 2Q2026).
For V8.5.0.0 through 8.5.5.29:
· Upgrade to minimal fix pack levels as required by the interim fix and then apply the Interim Fix that resolves PH71061
--OR--
· Apply Fix Pack 8.5.5.30 or later (targeted availability 3Q2026).
Additional interim fixes may be available and linked off the interim fix download page.
Important Note
IBM strongly suggests that all System z customers be subscribed to the System z Security Portal to receive the latest critical System z security and integrity service. If you are not subscribed, see the instructions on the System z Security web site. Security and integrity APARs and associated fixes will be posted to this portal. IBM suggests reviewing the CVSS scores and applying all security or integrity fixes as soon as possible to minimize any potential risk.
Workarounds and Mitigations
None
Get Notified about Future Security Bulletins
References
Acknowledgement
Change History
11 May 2026: Initial Publication
*The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin.
Disclaimer
According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES ""AS IS"" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY. In addition to other efforts to address potential vulnerabilities, IBM periodically updates the record of components contained in our product offerings. As part of that effort, if IBM identifies previously unidentified packages in a product/service inventory, we address relevant vulnerabilities regardless of CVE date. Inclusion of an older CVEID does not demonstrate that the referenced product has been used by IBM since that date, nor that IBM was aware of a vulnerability as of that date. We are making clients aware of relevant vulnerabilities as we become aware of them. "Affected Products and Versions" referenced in IBM Security Bulletins are intended to be only products and versions that are supported by IBM and have not passed their end-of-support or warranty date. Thus, failure to reference unsupported or extended-support products and versions in this Security Bulletin does not constitute a determination by IBM that they are unaffected by the vulnerability. Reference to one or more unsupported versions in this Security Bulletin shall not create an obligation for IBM to provide fixes for any unsupported or extended-support products or versions.
Document Location
Worldwide
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Document Information
Modified date:
11 May 2026
Initial Publish date:
11 May 2026
UID
ibm17272621