CVE-2026-33523

Apache HTTP Server: multiple modules: HTTP response splitting forwarding malicious status line

At a glance

Severity: MEDIUM 6.5
EPSS: EPSS 0.44 % · percentile 38 (2026-10-27)
State: PUBLISHED
Published: 2026-05-04
Updated: 2026-05-04
Assigner: apache
NVD status: Analyzed

Description

HTTP response splitting vulnerability in multiple Apache HTTP Server modules with untrusted or compromised backend servers. This issue affects Apache HTTP Server: from through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

Scores

Version	Score	Vector	Scored by
CVSS 3.1	MEDIUM 6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N	CISA-ADP
CVSS 3.1	MEDIUM 6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N	NVD · 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary)

Weaknesses (CWE)

CWE-443

European references

ENISA EUVD · EUVD-2026-26965
GCVE · GCVE-0-2026-33523

CERT-FR advisories

CERTFR-2026-AVI-0962 — Multiples vulnérabilités dans les produits Tenable · cert.ssi.gouv.fr
CERTFR-2026-AVI-0905 — Multiples vulnérabilités dans Tenable Security Center · cert.ssi.gouv.fr
CERTFR-2026-AVI-0608 — Multiples vulnérabilités dans Microsoft Azure Linux · cert.ssi.gouv.fr
CERTFR-2026-AVI-0530 — Multiples vulnérabilités dans Apache HTTP Server · cert.ssi.gouv.fr

Affected configurations (NVD CPE)

cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:* ≥ 2.4.0 < 2.4.67

Affected products

Product	Versions
Apache Software Foundation · Apache HTTP Server	affected 2.4.0 ≤ 2.4.66

References

Sources

Source	Licence
CVE List (CVEProject cvelistV5)	CVE Program Terms of Use
EPSS (FIRST.org)	FIRST — attribution requested
ENISA EUVD	ENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)	Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feeds	Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD