Apache HTTP Server: http2: double free and possible RCE on early reset
Summary
| CVE | CVE-2026-23918 |
|---|---|
| State | PUBLISHED |
| Assigner | apache |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-04 15:16:03 UTC |
| Updated | 2026-07-15 02:18:45 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v3.1 8.8 HIGH from ADP
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.458100000 probability, percentile 0.986670000 (date 2026-07-18)
Problem Types: CWE-415 | CWE-1341 | CWE-415 CWE-415 Double Free | CWE-1341 Multiple Releases of Same Resource or Handle
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | DECLARED | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | ADP | CVSS | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | Secondary | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Apache | Http Server | 2.4.66 | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Apache Software Foundation | Apache HTTP Server | affected 2.4.66 semver | Not specified |
| ADP | Red Hat | Red Hat Hardened Images | unaffected 2.4.67-0.1.hum1 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 7 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
| ADP | Red Hat | Red Hat JBoss Core Services | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| httpd.apache.org/security/vulnerabilities_24.html | [email protected] | httpd.apache.org | Vendor Advisory |
| access.redhat.com/errata/RHSA-2026:13938 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| www.openwall.com/lists/oss-security/2026/05/04/19 | af854a3a-2127-422b-91ae-364da2661108 | www.openwall.com | Mailing List, Third Party Advisory |
| access.redhat.com/security/cve/CVE-2026-23918 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23918.json | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | security.access.redhat.com | |
| bugzilla.redhat.com/show_bug.cgi | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | bugzilla.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Bartlomiej Dmitruk, striga.ai (en)
CNA: Stanislaw Strzalkowski, isec.pl (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2025-12-10T14:02:00.000Z | reported in PR 69899 |
| CNA | 2025-12-11T14:03:00.000Z | fixed in r1930444, r1930796 |
| ADP | 2026-05-04T15:01:41.066Z | Reported to Red Hat. |
| ADP | 2026-05-04T14:44:28.513Z | Made public. |
Solutions
ADP: RHSA-2026:13938: Red Hat Hardened Images
Workarounds
ADP: To mitigate this issue, disable the `mod_http2` module in your Apache HTTP Server configuration. This can be achieved by commenting out or removing the `LoadModule http2_module modules/mod_http2.so` line in the Apache configuration file (e.g., `/etc/httpd/conf.modules.d/00-base.conf` or a similar configuration file). After modifying the configuration, restart the httpd service for the changes to take effect. This action will impact services relying on HTTP/2 functionality.