CVE-2026-34356

⚠️ high

Summary

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.

CVSS Score

7.5

High

EPSS Score

0.7

Exploit Probability

Published Date

2026-06-08

First Seen: 2026-06-09

📊 Relative Risk Intelligence

This CVE is Moderate Risk - more severe than 69.0% of all 328,009 vulnerabilities in our database.

#101,817

Above average severity

Severity Percentile

🎯 CISA SSVC Assessment Updated: Jun 8, 2026

🔍 Exploitation Status

None

No known exploits

⚙️ Automatable

YES

Can be exploited automatically

💥 Technical Impact

Partial

Limited system impact

🏆 Discovered By

Arkadi Vainbrand depthfirst (depthfirst.com)

SSVC data provided by CISA

Last Modified 2026-06-09

Source NVD 🔗

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

CWE IDs (Weakness Types)

CWE-122

📦 Affected Products 1

Vendor	Product	Status	Affected Versions
apache	http_server	Affected	> 2.4.0 < 2.4.68

🔗 References 2

https://httpd.apache.org/security/vulnerabilities_24...

Vendor Advisory

http://www.openwall.com/lists/oss-security/2026/06/08/7

Mailing List

🔗 Related CVEs 6

CVE ID	Severity	CVSS	EPSS	Summary	Published
CVE-2026-29167	⛔ critical	9.8	0.7	Use After Free vulnerability in Apache HTTP Server with mod_ldap in per-directory configuration This issue affects Apac...	2026-06-08
CVE-2026-29170	🔶 medium	6.1	0.6	A cross-site scripting vulnerability exists in mod_proxy_ftp's HTML directory list generation in Apache HTTP Server 2.4....	2026-06-08
CVE-2026-34355	⚠️ high	7.5	0.6	A buffer overflow in mod_proxy_html in Apache HTTP Server 2.4.67 and earlier allows an attack by an untrusted backend. U...	2026-06-08
CVE-2026-42535	⛔ critical	9.1	0.6	A path handling issue in mod_dav_fs in Apache 2.4.67 and earlier allows a WebDAV content author to directly manipulate ...	2026-06-08
CVE-2026-42536	⚠️ high	7.5	0.5	Heap-based Buffer Overflow vulnerability in Apache HTTP Server with mod_xml2enc, xml2StartParse, and untrusted content ...	2026-06-08
CVE-2026-43951	🔶 medium	6.5	0.5	Out-of-bounds Read vulnerability in Apache HTTP Server with mod_headers and mod_mime and multiple response languages. T...	2026-06-08

These CVEs affect the same products