HTTP response splitting in the core of Apache HTTP Server allows an attacker who can manipulate the Content-Type response headers of applications hosted or proxied by the server can split the HTTP response. This vulnerability was described as CVE-2023-38709 but the patch included in Apache HTTP Server 2.4.59 did not address the issue. Users are recommended to upgrade to version 2.4.64, which fixes this issue.

[Web App Scanning] Apache 2.4.x < 2.4.64 Multiple Vulnerabilities

The remote Ubuntu 22.04 LTS / 24.04 LTS / 25.04 host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-7639-1 advisory.

    It was discovered that the Apache HTTP Server incorrectly handled certain Content-Type response headers. A     remote attacker could possibly use this issue to perform HTTP response splitting attacks. (CVE-2024-42516)

    xiaojunjie discovered that the Apache HTTP Server mod_proxy module incorrectly handled certain requests. A     remote attacker could possibly use this issue to send outbound proxy requests to an arbitrary URL.
    (CVE-2024-43204)

    John Runyon discovered that the Apache HTTP Server mod_ssl module incorrectly escaped certain data. A     remote attacker could possibly use this issue to insert escape characters into log files. (CVE-2024-47252)

    Sven Hebrok, Felix Cramer, Tim Storm, Maximilian Radoy, and Juraj Somorovsky discovered that the Apache     HTTP Server mod_ssl module incorrectly handled TLS 1.3 session resumption. A remote attacker could     possibly use this issue to bypass access control. (CVE-2025-23048)

    Anthony CORSIEZ discovered that the Apache HTTP Server mod_proxy_http2 module incorrectly handled missing     host headers. A remote attacker could possibly use this issue to cause the server to crash, resulting in a     denial of service. (CVE-2025-49630)

    Robert Merget discovered that the Apache HTTP Server mod_ssl module incorrectly handled TLS upgrades. A     remote attacker could possibly use this issue to hijack an HTTP session. This update removes the old     SSLEngine optional configuration option, possibly requiring a configuration change in certain     environments. (CVE-2025-49812)

    Gal Bar Nahum discovered that the Apache HTTP Server incorrectly handled certain memory operations. A     remote attacker could possibly use this issue to cause the server to consume resources, leading to a     denial of service. (CVE-2025-53020)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the 342f2a0a-5e9b-11f0-8baa-8447094a420f advisory.

    The Apache httpd project reports:
    moderate: Apache HTTP Server: HTTP response splitting (CVE-2024-42516)     low: Apache HTTP Server: SSRF with mod_headers setting Content-Type header (CVE-2024-43204)     moderate: Apache HTTP Server: SSRF on Windows due to UNC paths (CVE-2024-43394)     low: Apache HTTP Server: mod_ssl error log variable escaping (CVE-2024-47252)     moderate: Apache HTTP Server: mod_ssl access control bypass with session resumption (CVE-2025-23048)     low: Apache HTTP Server: mod_proxy_http2 denial of service (CVE-2025-49630)     moderate: Apache HTTP Server: mod_ssl TLS upgrade attack (CVE-2025-49812)     moderate: Apache HTTP Server: HTTP/2 DoS by Memory Increase (CVE-2025-53020)

Tenable has extracted the preceding description block directly from the FreeBSD security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of httpd installed on the remote host is prior to 2.4.64. It is, therefore, affected by multiple vulnerabilities as referenced in the SSA:2025-192-02 advisory.

    New httpd packages are available for Slackware 15.0 and -current to fix security issues.

Tenable has extracted the preceding description block directly from the httpd security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of Apache httpd installed on the remote host is prior to 2.4.64. It is, therefore, affected by multiple vulnerabilities as referenced in the 2.4.64 advisory.

  - In certain proxy configurations, a denial of service attack against Apache HTTP Server versions 2.4.26     through to 2.4.63 can be triggered by untrusted clients causing an assertion in mod_proxy_http2.
    Configurations affected are a reverse proxy is configured for an HTTP/2 backend, with ProxyPreserveHost     set to on. (CVE-2025-49630)

  - HTTP response splitting in the core of Apache HTTP Server allows an attacker who can manipulate the     Content-Type response headers of applications hosted or proxied by the server can split the HTTP response.
    This vulnerability was described as CVE-2023-38709 but the patch included in Apache HTTP Server 2.4.59 did     not address the issue. Users are recommended to upgrade to version 2.4.64, which fixes this issue.
    (CVE-2024-42516)

  - SSRF in Apache HTTP Server with mod_proxy loaded allows an attacker to send outbound proxy requests to a     URL controlled by the attacker. Requires an unlikely configuration where mod_headers is configured to     modify the Content-Type request or response header with a value provided in the HTTP request. Users are     recommended to upgrade to version 2.4.64 which fixes this issue. (CVE-2024-43204)

  - Server-Side Request Forgery (SSRF) in Apache HTTP Server on Windows allows to potentially leak NTLM hashes     to a malicious server via mod_rewrite or apache expressions that pass unvalidated request input. This     issue affects Apache HTTP Server: from 2.4.0 through 2.4.63. Note: The Apache HTTP Server Project will be     setting a higher bar for accepting vulnerability reports regarding SSRF via UNC paths. The server offers     limited protection against administrators directing the server to open UNC paths. Windows servers should     limit the hosts they will connect over via SMB based on the nature of NTLM authentication.
    (CVE-2024-43394)

  - Insufficient escaping of user-supplied data in mod_ssl in Apache HTTP Server 2.4.63 and earlier allows an     untrusted SSL/TLS client to insert escape characters into log files in some configurations. In a logging     configuration where CustomLog is used with %{varname}x or %{varname}c to log variables provided by     mod_ssl such as SSL_TLS_SNI, no escaping is performed by either mod_log_config or mod_ssl and unsanitized     data provided by the client may appear in log files. (CVE-2024-47252)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
242284	Ubuntu 22.04 LTS / 24.04 LTS / 25.04 : Apache HTTP Server vulnerabilities (USN-7639-1)	Nessus	Ubuntu Local Security Checks	critical
242028	FreeBSD : Apache httpd -- Multiple vulnerabilities (342f2a0a-5e9b-11f0-8baa-8447094a420f)	Nessus	FreeBSD Local Security Checks	high
242008	Slackware Linux 15.0 / current httpd Multiple Vulnerabilities (SSA:2025-192-02)	Nessus	Slackware Local Security Checks	high
241984	Apache 2.4.x < 2.4.64 Multiple Vulnerabilities	Nessus	Web Servers	high

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