CVE-2026-29168
Published: 05 May 2026
Description
Allocation of Resources Without Limits or Throttling vulnerability in Apache HTTP Server's mod_md via OCSP response data. This issue affects Apache HTTP Server: from 2.4.30 through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
This control implements explicit throttling on session allocation, addressing the weakness of allocating resources without limits.
Plan testing exercises resource allocation limits and throttling during simulated failures, directly addressing weaknesses that allow unbounded resource use.
Contingency plan updates ensure recovery strategies address unbounded resource allocation, making it harder for attackers to exploit lack of throttling to cause prolonged outages.
Provides continuity when unbounded resource allocation at the primary site leads to exhaustion and downtime.
Alternate services allow operations to continue when primary allocation of resources lacks limits or throttling.
Explicit planning of security-related actions requires defining limits, windows, and resource allocations, making allocation without throttling far less likely.
Measures of performance include tracking allocation behavior and throttling effectiveness, reducing the window for resource exhaustion attacks.
Imposes an inactivity-based limit on network resource allocation, throttling the number of concurrently held connections.
Security SummaryAI
CVE-2026-29168 is an Allocation of Resources Without Limits or Throttling vulnerability (CWE-770) in the mod_md module of the Apache HTTP Server, specifically triggered by OCSP response data. This flaw affects Apache HTTP Server versions from 2.4.30 through 2.4.66. It has a CVSS v3.1 base score of 7.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L), indicating high severity due to its network accessibility and low attack complexity.
A remote, unauthenticated attacker can exploit this vulnerability over the network without user interaction by sending crafted OCSP responses to the mod_md module. Successful exploitation allows partial impacts on confidentiality, integrity, and availability, potentially leading to resource exhaustion such as excessive memory allocation, which could result in denial-of-service conditions or minor data disruptions on affected servers.
The official Apache HTTP Server security advisory recommends upgrading to version 2.4.67, which addresses the issue. Additional details are available in the Apache vulnerabilities page at https://httpd.apache.org/security/vulnerabilities_24.html and the oss-security mailing list announcement at http://www.openwall.com/lists/oss-security/2026/05/05/6.
Details
- CWE(s)
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Vulnerability in public-facing Apache mod_md allows unauthenticated remote exploitation via crafted OCSP responses to trigger resource exhaustion/DoS (CWE-770), directly mapping to T1190 (Exploit Public-Facing Application) for initial access and T1499.004 (Application or System Exploitation) for endpoint DoS impact.