CVE-2026-56154
published 2026-10-01CVE-2026-56154: Use After Free vulnerability in Apache HTTP Server's mod_rewrite when using lookahead (%{LA-U:HTTP:...}) This issue affects Apache HTTP Server: from 2.4.0…
PriorityP356critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.54%
44.9th percentile
Use After Free vulnerability in Apache HTTP Server's mod_rewrite when using lookahead (%{LA-U:HTTP:...})
This issue affects Apache HTTP Server: from 2.4.0 through 2.4.68.
Affected
5 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| apache | http_server | >= 2.4.0 < 2.4.69 | 2.4.69 |
| apache | httpd | — | — |
| apache_software_foundation | apache_http_server | 2.4.0 – 2.4.68 | — |
| httpd_2.4 | httpd | — | — |
| ubuntu | apache2 | — | — |
CVSS provenance
nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vendor_redhat9.8CRITICAL
vendor_ubuntu9.8CRITICAL
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Ubuntu
Apache HTTP Server vulnerabilities
vendor_ubuntu·2026-10-07·CVSS 9.8
CVE-2026-59797 [CRITICAL] Apache HTTP Server vulnerabilities
Title: Apache HTTP Server vulnerabilities
Summary: Several security issues were fixed in Apache HTTP Server.
It was discovered that Apache HTTP Server's mod_rewrite module incorrectly
handled memory when performing certain variable lookups. A remote attacker
could possibly use this issue to cause a denial of service or execute
arbitrary code. (CVE-2026-56154)
Lucian Nitescu, Simon Kappel, and Gianluca Danesin discovered that Apache
HTTP Server's mod_http2 module incorrectly handled memory when processing
certain HTTP/2 connections. A remote attacker could possibly use this issue
to cause a denial of service or execute arbitrary code. This issue only
affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04
LTS, and Ubuntu 26.04 LTS. (CVE-2026-57941)
Juthawong Naisangu
Red Hat
httpd: httpd: Denial of Service via mod_rewrite lookahead
vendor_redhat·2026-10-01·CVSS 9.8
CVE-2026-56154 [CRITICAL] CWE-416 httpd: httpd: Denial of Service via mod_rewrite lookahead
httpd: httpd: Denial of Service via mod_rewrite lookahead
Use After Free vulnerability in Apache HTTP Server's mod_rewrite when using lookahead (%{LA-U:HTTP:...})
This issue affects Apache HTTP Server: from 2.4.0 through 2.4.68.
A use-after-free flaw was found in the mod_rewrite module of Apache HTTP Server when evaluating URL lookahead expressions that reference HTTP request headers, such as %{LA-U:HTTP:...}. A remote attacker may be able to trigger invalid memory access in a server using an affected rewrite configuration, potentially causing a denial of service or arbitrary code execution.
Statement: Red Hat initially assesses this issue as Important due to the potential for remote denial of service or code execution in affected mod_rewrite configurations. Exploitation requires URL lo
GHSA
Use After Free vulnerability in Apache HTTP Server's mod_rewrite when using lookahead (%{LA-U:HTTP:...}) This issue affects Apache HTTP Server: from 2.4.0 through 2.4.68.
ghsa_unreviewed·2026-10-01
CVE-2026-56154 [CRITICAL] CWE-416 Use After Free vulnerability in Apache HTTP Server's mod_rewrite when using lookahead (%{LA-U:HTTP:...}) This issue affects Apache HTTP Server: from 2.4.0 through 2.4.68.
Use After Free vulnerability in Apache HTTP Server's mod_rewrite when using lookahead (%{LA-U:HTTP:...})
This issue affects Apache HTTP Server: from 2.4.0 through 2.4.68.
No detection rules found.
No public exploits indexed.
2026-10-01
Published