Security Bulletin
Summary
There are multiple vulnerabilities in the IBM HTTP Server used by IBM WebSphere Application Server (CVE-2026-8834, CVE-2026-8852, CVE-2026-8856, CVE-2026-8850, CVE-2026-8854, CVE-2026-8855, CVE-2026-8835, CVE-2026-45186, CVE-2026-9170).
Vulnerability Details
CVEID: CVE-2026-8850
DESCRIPTION: IBM HTTP Server is vulnerable to denial of service via the optional module mod_ibm_upload.
CWE: CWE-476: NULL Pointer Dereference
CVSS Source: IBM
CVSS Base score: 7.5
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CVEID: CVE-2026-8855
DESCRIPTION: IBM HTTP Server is vulnerable to remote code execution and denial of service in configurations with TLS mutual authentication (client authentication).
CWE: CWE-94: Improper Control of Generation of Code ('Code Injection')
CVSS Source: IBM
CVSS Base score: 8.1
CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H)
CVEID: CVE-2026-8835
DESCRIPTION: IBM HTTP Server is vulnerable to invalid pointer dereference. A privileged user, authenticated to the Administration Server, could exploit this vulnerability to expose sensitive information or cause a denial of service.
CWE: CWE-822: Untrusted Pointer Dereference
CVSS Source: IBM
CVSS Base score: 7.3
CVSS Vector: (CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H)
CVEID: CVE-2026-8834
DESCRIPTION: IBM HTTP Server contains a buffer overflow vulnerability. A privileged user, authenticated to the Administration Server, could exploit this vulnerability to execute remote code or cause a denial of service.
CWE: CWE-122: Heap-based Buffer Overflow
CVSS Source: IBM
CVSS Base score: 8
CVSS Vector: (CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
CVEID: CVE-2026-8856
DESCRIPTION: IBM HTTP Server is vulnerable to denial of service in configurations where an attacker has write access to parts of the server configuration.
CWE: CWE-400: Uncontrolled Resource Consumption
CVSS Source: IBM
CVSS Base score: 7.7
CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H)
CVEID: CVE-2026-45186
DESCRIPTION: In libexpat before 2.8.1, the computational complexity of attribute name collision checks allows a denial of service via moderately sized crafted XML input.
CWE: CWE-407: Inefficient Algorithmic Complexity
CVSS Source: NVD
CVSS Base score: 7.5
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CVEID: CVE-2026-8852
DESCRIPTION: IBM HTTP Server is vulnerable to denial of service via the optional module mod_fastcgi module.
CWE: CWE-617: Reachable Assertion
CVSS Source: IBM
CVSS Base score: 6.2
CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CVEID: CVE-2026-8854
DESCRIPTION: IBM HTTP Server is vulnerable to denial of service via the optional module mod_mem_cache.
CWE: CWE-825: Expired Pointer Dereference
CVSS Source: IBM
CVSS Base score: 7.5
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
ID: CVE-2026-9170
DESCRIPTION: IBM HTTP Server is vulnerable to denial of service and a potential remote code execution due to improper input validation.
CWE: CWE-94: Improper Control of Generation of Code ('Code Injection')
CVSS Source: IBM
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)
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 PH71265.
For IBM HTTP Server used by IBM WebSphere Application Server:
For V9.0.0.0 through 9.0.5.28:
· Upgrade to minimal fix pack levels as required by the interim fix and then apply the Interim Fix that resolves PH71265
--OR--
· Apply Fix Pack 9.0.5.29 or later (targeted availability 3Q2026).
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 PH71265
--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
26 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:
26 May 2026
Initial Publish date:
26 May 2026
UID
ibm17274065