Cyber Resilience

CVE-2026-23918

Memory Safety in Apache Http Server 2.4.66

Memory Safety
Published
04 May 2026
Modified
15 July 2026
Patch / advisory
View advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.50 99th percentile
Risk Priority 84 floored blend · peak EPSS

Summary

CVE-2026-23918 is a high-severity Double Free (CWE-415) vulnerability in Apache Http Server. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked in the top 1% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-23918 is a double-free vulnerability, assigned CWE-415, that affects Apache HTTP Server version 2.4.66 when the HTTP/2 protocol is in use and can lead to remote code execution. The flaw resides in the server’s HTTP/2 handling code and carries a CVSS 3.1 base score of 8.8.

An authenticated remote attacker who can send crafted HTTP/2 requests to an affected server may trigger the double-free condition, potentially resulting in arbitrary code execution with the privileges of the httpd process.

The Apache project’s security page and the oss-security mailing list both state that users should upgrade to version 2.4.67, which contains the fix; no other mitigations are described in the references.

The associated EPSS score has remained flat at 0.0112 with no material increase since disclosure.

EU & UK References

Vulnerability Data

Double Free and possible RCE vulnerability in Apache HTTP Server with the HTTP/2 protocol. This issue affects Apache HTTP Server: 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

CWE(s)
CWE-415CWE-1341

Related Threats

MITRE ATT&CK Enterprise Techniques

T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-48913Same product: Apache Http Server
CVE-2026-34355Same product: Apache Http Server
CVE-2026-29167Same product: Apache Http Server
CVE-2026-44631Same product: Apache Http Server
CVE-2026-34356Same product: Apache Http Server
CVE-2026-42536Same product: Apache Http Server
CVE-2026-43951Same product: Apache Http Server
CVE-2026-34032Same product: Apache Http Server
CVE-2026-33857Same product: Apache Http Server
CVE-2026-28780Same product: Apache Http Server

Affected Assets

apache
http server
2.4.66

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 1 hardening rule · 1 OS baseline
Validate
Prove the fix (OWASP ASVS)

—

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation explicitly includes dynamic analysis and fuzzing that locate double-free defects before release.

SA-15 Development Process, Standards, and Tools partial match

Documented development standards and tools can enforce proper resource-acquisition/release patterns.

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles can require memory-safe allocation patterns or language features that structurally eliminate double-free opportunities.

SC-39 Process Isolation partial match

Process isolation confines the effects of erroneous handle releases to a single execution domain.

SI-2 Flaw Remediation partial match

Flaw remediation processes require identification and correction of memory-management defects such as double free once discovered.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 full match
prevents

Secure SDLC practices directly prevent double-free errors via static analysis, safe memory APIs, and testing.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect double-free conditions before release.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle includes memory-safety practices that can prevent double-free bugs.

A.8.26 Application security requirements partial match
prevents

Application security requirements can mandate memory-safety rules that reduce double-free risk.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure system architecture and engineering principles can prescribe safe memory-management patterns.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly address proper use of free() and similar functions.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248590 OL 8 must clear the page allocator to prevent use-after-free attacks. prevents CWE-415

References