CVE-2026-44185: Apache HTTP Server Buffer Overflow Flaw

CVE-2026-44185 Overview

CVE-2026-44185 is a buffer over-read vulnerability [CWE-126] in Apache HTTP Server. The flaw exists in the handling of outbound Online Certificate Status Protocol (OCSP) requests sent to an attacker-controlled OCSP responder. An adversary controlling the OCSP server can trigger the over-read and influence affected httpd processes over the network.

The issue affects Apache HTTP Server versions 2.4.0 through 2.4.67. The Apache HTTP Server Project addressed the vulnerability in version 2.4.68.

Critical Impact
A network attacker who controls an OCSP responder consulted by httpd can cause a buffer over-read, leading to limited disclosure of process memory, integrity impact, and availability impact on the web server.

Affected Products

Apache HTTP Server 2.4.0 through 2.4.67
Deployments configured to perform OCSP validation of client or peer certificates
Reverse proxy and TLS-terminating httpd instances reaching external OCSP responders

Discovery Timeline

2026-06-08 - CVE-2026-44185 published to NVD
2026-06-11 - Last updated in NVD database

Technical Details for CVE-2026-44185

Vulnerability Analysis

The vulnerability is classified as a buffer over-read [CWE-126], in which httpd reads beyond the bounds of an allocated buffer while processing OCSP response data. The defect is reachable when Apache HTTP Server issues an outbound OCSP request and parses the reply returned by the responder.

Because the responder URL is taken from certificate metadata or server configuration, an attacker who controls the OCSP endpoint can craft responses that drive the parser past the allocated buffer. Reading past the buffer can disclose adjacent process memory and may destabilize the worker handling the request.

The exposure surface is any Apache HTTP Server deployment that performs OCSP validation, including TLS-terminating front ends, reverse proxies validating backend certificates, and gateways performing mutual TLS.

Root Cause

The root cause is missing or insufficient bounds checking when parsing OCSP response fields received from a remote responder. The parser trusts length or structure information supplied by the responder and reads memory beyond the intended boundary. Public technical detail is limited; refer to the Apache HTTPD Vulnerabilities List and the Openwall OSS-Security Discussion for upstream context.

Attack Vector

Exploitation requires that httpd send an OCSP request to a responder the attacker controls. This typically occurs when a certificate presented to httpd references a malicious OCSP URL in its Authority Information Access (AIA) extension, or when configuration directs OCSP queries to an attacker-controlled host. No authentication or user interaction is required at the network layer.

// No verified public proof-of-concept code is available.
// Exploitation requires an attacker-controlled OCSP responder that returns
// a crafted response to an OCSP request issued by Apache httpd versions
// 2.4.0 through 2.4.67. See the Apache HTTPD vulnerabilities list for details.

Detection Methods for CVE-2026-44185

Indicators of Compromise

Outbound HTTP requests from httpd worker processes to unexpected OCSP responder hostnames
Repeated httpd worker crashes, segmentation faults, or mod_ssl errors logged near OCSP validation events
TLS handshakes that present client or peer certificates with AIA OCSP URLs pointing to untrusted domains

Detection Strategies

Inventory Apache HTTP Server hosts and identify any running versions 2.4.0 through 2.4.67
Inspect mod_ssl configuration for SSLOCSPEnable on and SSLOCSPDefaultResponder directives, and review their downstream destinations
Alert on httpd egress traffic to OCSP endpoints outside an allow-listed set of certificate authority responders

Monitoring Recommendations

Forward httpd error logs and TLS subsystem logs to a centralized analytics platform and alert on parsing or memory faults
Monitor process stability of httpd workers and correlate restarts with outbound OCSP activity
Capture DNS and proxy logs for OCSP hostname lookups initiated by web server hosts

How to Mitigate CVE-2026-44185

Immediate Actions Required

Upgrade Apache HTTP Server to version 2.4.68 or later on all affected hosts
Restrict outbound network access from httpd so OCSP traffic only reaches known certificate authority responders
Audit certificates accepted by httpd and reject those referencing untrusted OCSP URLs in their AIA extension

Patch Information

The Apache HTTP Server Project fixed CVE-2026-44185 in version 2.4.68. Administrators should upgrade using their distribution packages or the official source release. Refer to the Apache HTTPD Vulnerabilities List for the authoritative advisory and any downstream backport information.

Workarounds

Disable OCSP checking in mod_ssl by setting SSLOCSPEnable off where the patch cannot be applied immediately
Force OCSP requests through a controlled forward proxy that only permits requests to a vetted list of responders
Where supported, configure SSLOCSPDefaultResponder and SSLOCSPOverrideResponder on to route all OCSP queries to a trusted internal responder

bash

# Example mod_ssl configuration restricting OCSP behavior until patched
SSLOCSPEnable off

# Or, force OCSP queries to a trusted internal responder
SSLOCSPDefaultResponder "http://ocsp.internal.example.com/"
SSLOCSPOverrideResponder on