CWE-113 · Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')

CWE-113VariantIncomplete

Abstraction: Variant

Status: Incomplete

Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')

The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers.

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Related CAPECs

CAPEC-31

Accessing/Intercepting/Modifying HTTP Cookies

CAPEC-34

HTTP Response Splitting

CAPEC-85

AJAX Footprinting

CAPEC-105

HTTP Request Splitting

Related vulnerabilities

CVE-2026-38967CrowCpp Crow through v1.3.1 HTTP is vulnerable to response header injection via unvalidated response header values.

CVE-2023-25690Some mod_proxy configurations on Apache HTTP Server versions 2.4.0 through 2.4.55 allow a HTTP Request Smuggling attack. Configurations are affected when mod_proxy is enabled along with some form of RewriteRule or ProxyPassMatch in which a non-specific pattern matches some portion of the user-supplied request-target (URL) data and is then re-inserted into the proxied request-target using variable substitution. For example, something like: RewriteEngine on RewriteRule "^/here/(.*)" "http://example.com:8080/elsewhere?$1"; [P] ProxyPassReverse /here/ http://example.com:8080/ Request splitting/smuggling could result in bypass of access controls in the proxy server, proxying unintended URLs to existing origin servers, and cache poisoning. Users are recommended to update to at least version 2.4.56 of Apache HTTP Server.

CVE-2019-25101A vulnerability classified as critical has been found in OnShift TurboGears 1.0.11.10. This affects an unknown part of the file turbogears/controllers.py of the component HTTP Header Handler. The manipulation leads to http response splitting. It is possible to initiate the attack remotely. Upgrading to version 1.0.11.11 is able to address this issue. The patch is named f68bbaba47f4474e1da553aa51564a73e1d92a84. It is recommended to upgrade the affected component. The associated identifier of this vulnerability is VDB-220059.

CVE-2025-53007arduino-esp32 provides an Arduino core for the ESP32. Versions prior to 3.3.0-RC1 and 3.2.1 contain a HTTP Response Splitting vulnerability. The `sendHeader` function takes arbitrary input for the HTTP header name and value, concatenates them into an HTTP header line, and appends this to the outgoing HTTP response headers. There is no validation or sanitization of the `name` or `value` parameters before they are included in the HTTP response. If an attacker can control the input to `sendHeader` (either directly or indirectly), they could inject carriage return (`\r`) or line feed (`\n`) characters into either the header name or value. This could allow the attacker to inject additional headers, manipulate the structure of the HTTP response, potentially inject an entire new HTTP response (HTTP Response Splitting), and/or ause header confusion or other HTTP protocol attacks. Versions 3.3.0-RC1 and 3.2.1 contain a fix for the issue.

CVE-2025-55271HCL Aftermarket DPC is affected by HTTP Response Splitting vulnerability where in depending on how the web application handles the split response, an attacker may be able to execute arbitrary commands or inject harmful content into the response..

CVE-2024-52875An issue was discovered in GFI Kerio Control 9.2.5 through 9.4.5. The dest GET parameter passed to the /nonauth/addCertException.cs and /nonauth/guestConfirm.cs and /nonauth/expiration.cs pages is not properly sanitized before being used to generate a Location HTTP header in a 302 HTTP response. This can be exploited to perform Open Redirect or HTTP Response Splitting attacks, which in turn lead to Reflected Cross-Site Scripting (XSS). Remote command execution can be achieved by leveraging the upgrade feature in the admin interface.

CVE-2023-32708In Splunk Enterprise versions below 9.0.5, 8.2.11, and 8.1.14, and Splunk Cloud Platform versions below 9.0.2303.100, a low-privileged user can trigger an HTTP response splitting vulnerability with the ‘rest’ SPL command that lets them potentially access other REST endpoints in the system arbitrarily.

CVE-2021-40336A vulnerability exists in the http web interface where the web interface does not validate data in an HTTP header. This causes a possible HTTP response splitting, which if exploited could lead an attacker to channel down harmful code into the user’s web browser, such as to steal the session cookies. Thus, an attacker who successfully makes an MSM user who has already established a session to MSM web interface clicks a forged link to the MSM web interface, e.g., the link is sent per E-Mail, could trick the user into downloading malicious software onto his computer. This issue affects: Hitachi Energy MSM V2.2 and prior versions.

CVE-2021-33621The cgi gem before 0.1.0.2, 0.2.x before 0.2.2, and 0.3.x before 0.3.5 for Ruby allows HTTP response splitting. This is relevant to applications that use untrusted user input either to generate an HTTP response or to create a CGI::Cookie object.

CVE-2018-13814A vulnerability has been identified in SIMATIC HMI Comfort Panels 4" - 22" (All versions < V14), SIMATIC HMI Comfort Outdoor Panels 7" & 15" (All versions < V14), SIMATIC HMI KTP Mobile Panels KTP400F, KTP700, KTP700F, KTP900 and KTP900F (All versions < V14), SIMATIC WinCC Runtime Advanced (All versions < V14), SIMATIC WinCC Runtime Professional (All versions < V14), SIMATIC WinCC (TIA Portal) (All versions < V14), SIMATIC HMI Classic Devices (TP/MP/OP/MP Mobile Panel) (All versions). The integrated web server (port 80/tcp and port 443/tcp) of the affected devices could allow an attacker to inject HTTP headers. An attacker must trick a valid user who is authenticated to the device into clicking on a malicious link to exploit the vulnerability. At the time of advisory publication no public exploitation of this security vulnerability was known.

CVE-2018-11347The YunoHost 2.7.2 through 2.7.14 web application is affected by one HTTP Response Header Injection. This flaw allows an attacker to inject, into the response from the server, one or several HTTP Header. It requires an interaction with the user to send him the malicious link. It could be used to perform other attacks such as user redirection to a malicious website, HTTP response splitting, or HTTP cache poisoning.

CVE-2025-61689HTTP.jl is an HTTP client and server functionality for the Julia programming language. Prior to version 1.10.19, HTTP.jl did not validate header names/values for illegal characters, allowing CRLF-based header injection and response splitting. This enables HTTP response splitting and header injection, leading to cache poisoning, XSS, session fixation, and more. This issue is fixed in HTTP.jl `v1.10.19`.

CVE-2018-3911An exploitable HTTP header injection vulnerability exists in the remote servers of Samsung SmartThings Hub STH-ETH-250 - Firmware version 0.20.17. The hubCore process listens on port 39500 and relays any unauthenticated message to SmartThings' remote servers, which insecurely handle JSON messages, leading to partially controlled requests generated toward the internal video-core process. An attacker can send an HTTP request to trigger this vulnerability.

CVE-2024-23644Trillium is a composable toolkit for building internet applications with async rust. In `trillium-http` prior to 0.3.12 and `trillium-client` prior to 0.5.4, insufficient validation of outbound header values may lead to request splitting or response splitting attacks in scenarios where attackers have sufficient control over headers. This only affects use cases where attackers have control of request headers, and can insert "\r\n" sequences. Specifically, if untrusted and unvalidated input is inserted into header names or values. Outbound `trillium_http::HeaderValue` and `trillium_http::HeaderName` can be constructed infallibly and were not checked for illegal bytes when sending requests from the client or responses from the server. Thus, if an attacker has sufficient control over header values (or names) in a request or response that they could inject `\r\n` sequences, they could get the client and server out of sync, and then pivot to gain control over other parts of requests or responses. (i.e. exfiltrating data from other requests, SSRF, etc.) In `trillium-http` versions 0.3.12 and later, if a header name is invalid in server response headers, the specific header and any associated values are omitted from network transmission. Additionally, if a header value is invalid in server response headers, the individual header value is omitted from network transmission. Other headers values with the same header name will still be sent. In `trillium-client` versions 0.5.4 and later, if any header name or header value is invalid in the client request headers, awaiting the client Conn returns an `Error::MalformedHeader` prior to any network access. As a workaround, Trillium services and client applications should sanitize or validate untrusted input that is included in header values and header names. Carriage return, newline, and null characters are not allowed.