CVE-2026-34356

Description

Heap-based Buffer Overflow vulnerability in Apache HTTP Server with malicious backend servers and ProxyPassReverseCookie* This issue affects Apache HTTP Server: from 2.4.0 through 2.4.67. Users are recommended to upgrade to version 2.4.68, which fixes the issue.

Description (MITRE) cveawg.mitre.org

Pulled from cveawg.mitre.org/api/cve/CVE-2026-34356 on 2026-10-29. Shown when MITRE's text differs from the cvelistV5 mirror.

Heap-based Buffer Overflow vulnerability in Apache HTTP Server with malicious backend servers and ProxyPassReverseCookie* This issue affects Apache HTTP Server: from 2.4.0 through 2.4.67. Users are recommended to upgrade to version 2.4.68, which fixes the issue.

Overview

State

—

Assigner (CNA)

—

CVSS severity

high

CVSS score

7.5 / 10

CVSS vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Effective score

7.5 / 10 HIGH source: CNA overview

MSRC score

7.5 / 10 HIGH MS rating: Moderate

CWE(s)

CWE-122

Reserved

—

Published

2026-06-09 07:00 UTC

Last updated

2026-06-20 01:43 UTC

Source

https://www.tenable.com/cve/CVE-2026-34356

Linked Threat

CVE-2026-34356 — CVE-2026-34356

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published

2026-06-08 16:16:38 UTC

NVD last modified

2026-07-23 07:10:00 UTC

NVD CVSS v3.1

7.5 / 10 HIGH source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitability subscore

3.9 / 10

Impact subscore

3.6 / 10

EPSS score

0.0071 (probability of exploitation in next 30 days)

EPSS percentile

49.91% vs all CVEs — higher = more likely to be exploited, as of 2026-08-01

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID

EUVD-2026-35089

Assigner

apache

Published

Jun 8, 2026, 3:12:21 PM

Updated

Jun 8, 2026, 10:32:24 PM

EUVD base score (CVSS 3.1)

7.5 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EUVD-reported EPSS

0.7100

Vendors

Apache Software Foundation

Products

Apache HTTP Server (2.4.0 ≤2.4.67)

Aliases

GHSA-9gq3-xc6j-h3g5

ENISA description: Heap-based Buffer Overflow vulnerability in Apache HTTP Server with malicious backend servers and ProxyPassReverseCookie* This issue affects Apache HTTP Server: from 2.4.0 through 2.4.67. Users are recommended to upgrade to version 2.4.68, which fixes the issue.

Microsoft Security Response Center MSRC

Microsoft's vendor-authoritative record from the Security Update Guide — its own CVSS score, impact, severity rating, exploit assessment, and KB-article fixes. Refreshed 2026-11-04 03:30 UTC (source: CVRF).

MS severity

Moderate

MS CVSS base score

7.5 / 10 (temporal 6.9)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U

Release

2026-Jun

Vendor references (0)

References embedded in the original CVE record by the assigning CNA.

None in the CVE record.

Web references (5)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

• MSRC update guide: CVE-2026-34356 msrc
• http://www.openwall.com/lists/oss-security/2026/06/08/7 tenable:www.openwall.com
• https://httpd.apache.org/security/vulnerabilities_24.html tenable:httpd.apache.org
• https://nvd.nist.gov/vuln/detail/CVE-2026-34356 tenable:nvd.nist.gov
• https://www.cve.org/CVERecord?id=CVE-2026-34356 tenable:www.cve.org

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

• Microsoft Confirms Defender RoguePlanet 0-Day Exploit and Working to ...
  web:cybersecuritynews.com

  Microsoft has officially acknowledged a critical zero-day vulnerability in Microsoft Defender, publicly dubbed "RoguePlanet," and confirmed it is actively developing a security patch to address the flaw.

  2026-06-19 02:37 UTC
• Security Advisories and Bulletins | Microsoft Learn
  web:learn.microsoft.com

  In this library you will find the following security documents that have been released by the Microsoft Security Response Center (MSRC). The MSRC investigates all reports of security vulnerabilities affecting Microsoft products and services, and releases these documents as part of the ongoing effort to help you manage security risks and help keep your systems protected. Please use the ...

  2026-06-19 02:37 UTC
• Security Update Guide - Loading - Microsoft
  web:portal.msrc.microsoft.com

  The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

  2026-06-19 02:37 UTC
• Microsoft Confirms RoguePlanet Defender Zero-Day, Says Patch is in ...
  web:thehackernews.com

  Microsoft is preparing a patch for RoguePlanet, a Defender flaw tracked as CVE - 2026 -50656 that can enable privilege escalation.

  2026-06-19 02:37 UTC
• CVE-2026-34356: Apache HTTP Server Buffer Overflow Vulnerability in ...
  web:vulert.com

  CVE-2026-34356 is a high-severity buffer overflow vulnerability in Apache HTTP Server affecting versions 2.4.0 to 2.4.67. Upgrade to 2.4.68 to mitigate risks.

  2026-06-19 02:37 UTC
• Critical Patches Issued for Microsoft Products, April 14, 2026
  web:www.cisecurity.org

  <p>Multiple vulnerabilities have been discovered in Microsoft products, the most severe of which could allow for remote code execution. Successful exploitation of the most severe of these vulnerabilities could result in an attacker gaining the same privileges as the logged-on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or ...

  2026-06-19 02:37 UTC
• May 2026 Patch Tuesday: Updates and Analysis | CrowdStrike
  web:www.crowdstrike.com

  Microsoft has released security updates for 130 vulnerabilities, including 30 critical, in its May 2026 Patch Tuesday rollout.

  2026-06-19 02:37 UTC
• Microsoft Confirms It Is Urgently Working On Patch For ... - LinkedIn
  web:www.linkedin.com

  Microsoft has confirmed that it is developing a security update to address a newly disclosed zero-day vulnerability in Microsoft Defender, following the public release of exploit code that ...

  2026-06-19 02:37 UTC
• Microsoft working on a fix for RoguePlanet, a flaw that grants full PC ...
  web:www.malwarebytes.com

  Microsoft says it's working on a fix for an unpatched Defender vulnerability that can give attackers the highest level of access on Windows.

  2026-06-19 02:37 UTC
• Patch Tuesday June 2026: Security Updates & CVE Analysis
  web:zecurit.com

  Get the complete breakdown of Microsoft's June 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

  2026-06-19 02:37 UTC

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