CVE-2026-56449
Description
A flaw was found in the mod_proxy_html module of Apache HTTP Server. An attacker who controls or manipulates HTTP response bodies processed by the proxy can trigger an out-of-bounds memory write. This issue can cause the server process to crash, resulting in a Denial of Service (DoS).
Mitigation
Disable the `mod_proxy_html` module if HTML link rewriting is not required:
1. Comment out the module loader directive in `/etc/httpd/conf.modules.d/00-proxyhtml.conf`:
# sed -i 's/^\s*LoadModule proxy_html_module/#&/' /etc/httpd/conf.modules.d/00-proxyhtml.confAlternatively, set `ProxyHTMLEnable Off` in the affected server or virtual host configuration.
2. Reload the Apache HTTP Server:
# systemctl reload httpd
Caveats:
Disabling `mod_proxy_html` or turning off `ProxyHTMLEnable` halts automated rewriting of URLs in proxied HTML responses, which may break web applications that depend on backend path translation.
Warning: Reloading or restarting the `httpd` service may temporarily interrupt active network connections.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 3.7 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | None | N/A | None |
| Availability Impact | Low | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
Frequently Asked Questions
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