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CVE-2026-8854 IBM CVE debrief

IBM HTTP Server versions 8.5 (prior to 8.5.5.30) and 9.0 (prior to 9.0.5.29) contain a denial-of-service vulnerability in the optional mod_mem_cache module. The flaw, classified as CWE-825 (Expired Pointer Dereference), allows network-based attackers to trigger high availability impact without authentication. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) indicates the vulnerability is exploitable over the network with low attack complexity, requiring no privileges or user interaction. IBM has released security updates addressing this issue. Organizations running affected versions with mod_mem_cache enabled should prioritize patching, as the module is optional and may not be deployed in all configurations.

Vendor
IBM
Product
HTTP Server
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-26
Original CVE updated
2026-05-26
Advisory published
2026-05-26
Advisory updated
2026-05-26

Who should care

Organizations running IBM HTTP Server 8.5 or 9.0 with mod_mem_cache enabled, particularly those hosting public-facing web services where availability is critical.

Technical summary

The vulnerability exists in the optional mod_mem_cache module of IBM HTTP Server. An expired pointer dereference (CWE-825) can be triggered remotely, resulting in denial of service. The attack surface is network-accessible and requires no authentication. Fixed versions are 8.5.5.30 and 9.0.5.29.

Defensive priority

HIGH

Recommended defensive actions

  • Verify IBM HTTP Server version and identify systems running affected releases (8.5.x prior to 8.5.5.30, 9.0.x prior to 9.0.5.29)
  • Confirm whether mod_mem_cache module is enabled in httpd.conf configuration
  • Apply IBM security updates to reach fixed versions 8.5.5.30 or 9.0.5.29 or later
  • If patching is not immediately feasible and mod_mem_cache is not required, disable the module as a temporary risk reduction measure
  • Monitor IBM support resources for additional guidance or interim fixes

Evidence notes

Vulnerability affects mod_mem_cache module specifically; other IBM HTTP Server configurations without this module enabled are not vulnerable. CPE data confirms affected version ranges: 8.5.0.0 through 8.5.5.29 and 9.0.0.0 through 9.0.5.28.

Official resources

IBM PSIRT disclosed this vulnerability on 2026-05-26. The CVE was published and analyzed by NVD on the same date with a subsequent modification to the record on 2026-05-26. No known exploitation in ransomware campaigns has been reported.