CVE-2026-23918: Apache HTTP Server: http2: double free and possible RCE on early reset

Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified

What, why and how

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.

What

Why

The product calls free() twice on the same memory address.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Why

The product calls free() twice on the same memory address.

How

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path: a network path → Double Free → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface: Network
Privileges required: Low: a basic authenticated account is required
User interaction: None
Attack complexity: Low: no specialised conditions are recorded
Security boundary: Unchanged: impact remains within the vulnerable component's security authority
Weakness ? CWE means Common Weakness Enumeration: a standard category for the underlying weakness.: CWE-415 ↗
CWE-415: Double Free. The product calls free() twice on the same memory address.
CVSS vector ? CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land: No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.

NetworkCWE-415

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-26955Official EUVD mapping

0 linked advisory records.

Official EUVD record

BSI · German · WID-SEC-W-2026-2543Apple macOS (Tahoe, Sonoma und Sequoia): Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Apple macOS Tahoe, Sonoma und Sequoia ausnutzen, um seine Privilegien zu erhöhen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren, und um Sicherheitsvorkehrungen zu umgehen.

Official advisory

BSI · German · WID-SEC-W-2026-1354Apache HTTP Server: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Apache HTTP Server ausnutzen, um erweiterte Privilegien zu erlangen, beliebigen Code auszuführen, Sicherheitsmaßnahmen zu umgehen, vertrauliche Informationen offenzulegen oder einen Denial-of-Service-Zustand zu verursachen.

Official advisory

CERT-FR · French · CERTFR-2026-AVI-0962Multiples vulnérabilités dans les produits Tenable

CVERecord?id=CVE-2026-18667 Référence CVE CVE-2026-2003 https://www.cve.org/CVERecord?id=CVE-2026-2003 Référence CVE CVE-2026-2004 https://www.cve.org/CVERecord?id=CVE-2026-2004 Référence CVE CVE-2026-2005 https://www.cve.org/CVERecord?id=CVE-2026-2005 Référence CVE CVE-2026-2006 https://www.cve.org/CVERecord?id=CVE-2026-2006 Référence CVE CVE-2026-22795 https://www.cve.org/CVERecord?id=CVE-2026-22795 Référence CVE CVE-2026-22796 https://www.cve.org/CVERecord?id=CVE-2026-22796 Référence CVE CVE-2026-23479 https://www.cve.org/CVERecord?id=CVE-2026-23479 Référence CVE CVE-2026-23631 https://www.cve.org/CVERecord?id=CVE-2026-23631 Référence CVE CVE-2026-23918 https://www.cve.org/CVERecord?id=CVE-2026-23918 Référence CVE CVE-2026-24072 https://www.cve.org/CVERecord?id=CVE-2026-24072 Référence CVE CVE-2026-25243 https://www.cve.org/CVERecord?id=CVE-2026-25243 Référence CVE CVE-2026-25588 https://www.cve.org/CVERecord?id=CVE-2026-25588 Référence CVE CVE-2026-25589 https://www.cve.org/CVERecord?id=CVE-2026-25589 Référence CVE CVE-2026-33523 https://www.cve.org/CVERecord?id=CVE-2026-33523 Référence CVE CVE-2026-33857 https://www.cve.org/CVERecord?id=CVE-2026-33857 Référence CVE CVE-2026-34032 https://www.cve.org/CVERecord?id=CVE-2026-34032 Référence CVE CVE-2026-34059 https://www.cve.org/CVERecord?id=

Official advisory

CERT-FR · French · CERTFR-2026-AVI-0938Multiples vulnérabilités dans les produits Apple

pple.com/en-us/128068 Bulletin de sécurité Apple 128069 du 27 juillet 2026 https://support.apple.com/en-us/128069 Bulletin de sécurité Apple 128070 du 27 juillet 2026 https://support.apple.com/en-us/128070 Bulletin de sécurité Apple 128071 du 27 juillet 2026 https://support.apple.com/en-us/128071 Bulletin de sécurité Apple 128072 du 27 juillet 2026 https://support.apple.com/en-us/128072 Bulletin de sécurité Apple 128073 du 27 juillet 2026 https://support.apple.com/en-us/128073 Référence CVE CVE-2025-43325 https://www.cve.org/CVERecord?id=CVE-2025-43325 Référence CVE CVE-2026-20672 https://www.cve.org/CVERecord?id=CVE-2026-20672 Référence CVE CVE-2026-23918 https://www.cve.org/CVERecord?id=CVE-2026-23918 Référence CVE CVE-2026-28849 https://www.cve.org/CVERecord?id=CVE-2026-28849 Référence CVE CVE-2026-28896 https://www.cve.org/CVERecord?id=CVE-2026-28896 Référence CVE CVE-2026-28900 https://www.cve.org/CVERecord?id=CVE-2026-28900 Référence CVE CVE-2026-28911 https://www.cve.org/CVERecord?id=CVE-2026-28911 Référence CVE CVE-2026-28912 https://www.cve.org/CVERecord?id=CVE-2026-28912 Référence CVE CVE-2026-28914 https://www.cve.org/CVERecord?id=CVE-2026-28914 Référence CVE CVE-2026-28926 https://www.cve.org/CVERecord?id=CVE-2026-28926 Référence CVE CVE-2026-28928 https://www.cve.org/CVERecord?id=

Official advisory

CERT-FR · French · CERTFR-2026-AVI-0905Multiples vulnérabilités dans Tenable Security Center

CVERecord?id=CVE-2025-69421 Référence CVE CVE-2026-2003 https://www.cve.org/CVERecord?id=CVE-2026-2003 Référence CVE CVE-2026-2004 https://www.cve.org/CVERecord?id=CVE-2026-2004 Référence CVE CVE-2026-2005 https://www.cve.org/CVERecord?id=CVE-2026-2005 Référence CVE CVE-2026-2006 https://www.cve.org/CVERecord?id=CVE-2026-2006 Référence CVE CVE-2026-22795 https://www.cve.org/CVERecord?id=CVE-2026-22795 Référence CVE CVE-2026-22796 https://www.cve.org/CVERecord?id=CVE-2026-22796 Référence CVE CVE-2026-23479 https://www.cve.org/CVERecord?id=CVE-2026-23479 Référence CVE CVE-2026-23631 https://www.cve.org/CVERecord?id=CVE-2026-23631 Référence CVE CVE-2026-23918 https://www.cve.org/CVERecord?id=CVE-2026-23918 Référence CVE CVE-2026-24072 https://www.cve.org/CVERecord?id=CVE-2026-24072 Référence CVE CVE-2026-25243 https://www.cve.org/CVERecord?id=CVE-2026-25243 Référence CVE CVE-2026-25588 https://www.cve.org/CVERecord?id=CVE-2026-25588 Référence CVE CVE-2026-25589 https://www.cve.org/CVERecord?id=CVE-2026-25589 Référence CVE CVE-2026-33523 https://www.cve.org/CVERecord?id=CVE-2026-33523 Référence CVE CVE-2026-33857 https://www.cve.org/CVERecord?id=CVE-2026-33857 Référence CVE CVE-2026-34032 https://www.cve.org/CVERecord?id=CVE-2026-34032 Référence CVE CVE-2026-34059 https://www.cve.org/CVERecord?id=

Official advisory

CERT-FR · French · CERTFR-2026-AVI-0608Multiples vulnérabilités dans Microsoft Azure Linux

De multiples vulnérabilités ont été découvertes dans Microsoft Azure Linux. Elles permettent à un attaquant de provoquer un problème de sécurité non spécifié par l'éditeur.

Official advisory

CERT-FR · French · CERTFR-2026-AVI-0530Multiples vulnérabilités dans Apache HTTP Server

De multiples vulnérabilités ont été découvertes dans Apache HTTP Server. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance, une élévation de privilèges et un déni de service à distance.

Official advisory

NBSZ-NKI · Hungarian · cve-2026-23918CVE-2026-23918

Magas

Official advisory

NCSC-NL · Dutch · NCSC-2026-0267Kwetsbaarheden verholpen in Apple MacOS

Apache HTTP Server 2.4.66 contains a critical double free vulnerability in its HTTP/2 implementation that allows remote code execution, along with multiple other security flaws including privilege escalation, denial of service, and information disclosure.

Official advisory

NCSC-NL · Dutch · NCSC-2026-0134Kwetsbaarheden verholpen in Apache HTTP Server

Apache HTTP Server 2.4.66 contains a critical double free vulnerability in its HTTP/2 implementation that enables remote code execution, fixed in version 2.4.67.

Official advisory

Patch and workaround

Operational remediation based on structured source evidence.

Status ? Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.: Fix not verified
Affected: 2.4.66
Fixed: No fixed version is explicitly recorded in the structured CVE data.
Action: No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
Workaround: No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.

Evidence and provenance

Published 4 May 2026 · Last source change 15 Jul 2026, 01:17 UTC · CWE-415 · Double Free

CVE recordCVE.org · 5.2

CVSS sourceCISA ADP

EPSS source

The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.

FIRST · tracked since 2026-08-14

European sourceENISA EUVD · EUVD-2026-26955

Product sourceCNA

Remediation sourceCVE/CNA references

CWE sourceCNA

NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

2026-05-04CVE published

ENISA EUVD · EUVD-2026-26955↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗

Technical terms and abbreviations used in this report

CVE: Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS: Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS: Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE: Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA: CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP: Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD: National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT: A computer security incident response team that publishes warnings or coordinates incident response.
PoC: Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF: Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL: Living off the land: abuse of legitimate tools or system functions during an attack.

Apache HTTP Server: http2: double free and possible RCE on early reset

National CERT insights
?
CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

ENISA European Vulnerability Database

EUVD-2026-26955

What, why and how

Exploit reality and attack path

Official authority intelligence

Patch and workaround

Evidence and provenance

What changed after publication

Apache HTTP Server: http2: double free and possible RCE on early reset

National CERT insights ?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

EUVD-2026-26955

What, why and how

Exploit reality and attack path

Official authority intelligence

Patch and workaround

Evidence and provenance

National CERT insights
?
CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.