Security readout for executives and security teams
Plain-English summary
Apache HTTP Server 2.4.66 has a high-severity HTTP/2 memory handling flaw. Under the right conditions, it may let an attacker cause serious compromise, including possible remote code execution. The published fix is Apache HTTP Server 2.4.67.
Executive priority
Treat this as urgent for exposed Apache 2.4.66 systems, especially those serving HTTP/2. The business risk is potential full compromise of affected servers. Absence of cited active exploitation lowers emergency certainty, not remediation priority.
Technical view
The issue is described as a double free in Apache HTTP Server’s HTTP/2 handling on early reset. Sources list Apache HTTP Server 2.4.66 as affected and 2.4.67 as fixed. CVSS 3.1 is 8.8 with network attack vector, low complexity, low privileges, no user interaction, and high CIA impact.
Likely exposure
Exposure appears limited to Apache HTTP Server 2.4.66 deployments using HTTP/2. Internet-facing servers and reverse proxies deserve priority. The bundle does not identify additional affected versions or products.
Exploitation context
No provided source or KEV status indicates active exploitation. The vulnerability is serious because it is network-reachable and may allow RCE, but exploit availability and real-world exploitation are not established in the bundle.
Researcher notes
Track this as CWE-415 double free and CWE-1341. Validate exposure by exact Apache version, HTTP/2 configuration, and vendor package status. Do not assume unaffected or affected status beyond the source-listed 2.4.66 without vendor confirmation.
Mitigation direction
- Upgrade Apache HTTP Server 2.4.66 to 2.4.67.
- For Red Hat systems, review RHSA-2026:13938 applicability.
- Prioritize internet-facing HTTP/2-enabled Apache servers.
- If immediate upgrade is blocked, follow vendor guidance for temporary risk reduction.
Validation and detection
- Inventory Apache HTTP Server versions across production and edge systems.
- Confirm whether HTTP/2 is enabled on Apache 2.4.66 hosts.
- Check vendor package advisories for backported fixes.
- Verify upgraded systems report 2.4.67 or vendor-fixed packages.
- Document any remaining 2.4.66 exceptions and owners.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-1341: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-415: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-23918 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H2.85.9CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H2.85.9redhat-SADPVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- Source timelineapache
reported in PR 69899
- Source timelineapache
fixed in r1930444, r1930796
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-05-04T15:01:41.066Z: Reported to Red Hat.
- 2026-05-04T14:44:28.513Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://httpd.apache.org/security/vulnerabilities_24.htmlCVE reference, apache · vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-23918CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2465304CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23918.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:13938CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Multiple Releases of Same Resource or Handle
Multiple Releases of Same Resource or Handle represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Double Free
Double Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.