Weakness (CWE)
CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers
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.
More detail
HTTP agents or components may include a web server, load balancer, reverse proxy, web caching proxy, application firewall, web browser, etc. Regardless of the role, they are expected to maintain coherent, consistent HTTP communication state across all components. However, including unexpected data in an HTTP header allows an attacker to specify the entirety of the HTTP message that is rendered by the client HTTP agent (e.g., web browser) or back-end HTTP agent (e.g., web server), whether the message is part of a request or a response.
When an HTTP request contains unexpected CR and LF characters, the server may respond with an output stream that is interpreted as "splitting" the stream into two different HTTP messages instead of one. CR is carriage return, also given by %0d or \r, and LF is line feed, also given by %0a or \n.
In addition to CR and LF characters, other valid/RFC compliant special characters and unique character encodings can be utilized, such as HT (horizontal tab, also given by %09 or \t) and SP (space, also given as + sign or %20).
These types of unvalidated and unexpected data in HTTP message headers allow an attacker to control the second "split" message to mount attacks such as server-side request forgery, cross-site scripting, and cache poisoning attacks.
How to prevent it (4 mitigations)
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Implementation
Construct HTTP headers very carefully, avoiding the use of non-validated input data.
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Implementation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. If an input does not strictly conform to specifications, reject it or transform it into something that conforms.
When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
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Implementation
Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.
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Implementation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
Source: MITRE CWE-113
72 results · Clear filters · Feed
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Medium 6.5
HCL AION is affected by multiple security vulnerabilities.
HCL AION is affected by a vulnerability where user-controlled input could be included in HTTP response headers without proper neutralization of CR/LF characters. This may allow an attacker to inject headers or split responses, potentially resulting in uninten…
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Medium 4.3
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Dancer2 versions before 2.2.0 for Perl do not strip CR and LF from response header names in headers_to_array
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Medium 6.3
oRPC: Vary Header Injection in CORS Plugin leading to potential Cache/CORS Bypass
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Medium 4.8
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Medium 5.4
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Medium 5.4
Tornado before 6.4.1 CRLF Injection via CurlAsyncHTTPClient
Tornado before 6.4.1 contains a CRLF injection vulnerability in CurlAsyncHTTPClient that fails to reject carriage return and line feed characters in request headers. Attackers can inject CRLF sequences into header values to inject arbitrary headers or constru…
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Medium 5.4
Ajaxify Comments < 3.2 - Unauthenticated HTTP Header Injection
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Medium 5.3
cpp-httplib: CRLF injection via unvalidated HTTP trailer headers in chunked response writing
cpp-httplib is a C++ header-only HTTP/HTTPS library. In version 0.49.0, the chunked-response trailer output path writes trailer header names and values directly to the socket without validating them, allowing CRLF sequences in a trailer field to inject additi…
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Medium 6.8
ePA 3.x Integration: HTTP Header Injection in VAU Inner Requests
ePA 3.x Integration implements the authorization workflow and writes Medical Information Objects to Germany's electronic patient record. Prior to 1.3.0, ePA 3.x Integration does not neutralize CRLF characters in values used by app/vau/VAUProtokoll.py to const…
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Medium 5.3
swift-nio-http2: Missing CR/LF/NUL validation in header values
SwiftNIO HTTP/2 was missing validation on inbound HEADERS frames that let CR, LF, NUL, SP and other control characters reach an HTTP/1.1 backend through NIOHTTP2's HTTP/2-to-HTTP/1 codec, enabling HTTP request smuggling or response splitting. This vulnerabili…
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Medium 4.7
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Medium 6.9
Kirby: Request header injection in `Http\Remote`
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Medium 6.5
Hono - Vary Header Injection in CORS Middleware
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Medium 4.8
guzzlehttp/psr7: CRLF Injection in HTTP Start-Line Serialization
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Medium 5.3
Hono - Missing Cookie Name Validation in setCookie()
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Medium 6.5
Apache CXF: OAuth2: HTTP Response Splitting via WWW-Authenticate Realm Injection
A CRLF injection vulnerability exists in the OAuth2 AuthorizationUtils class. When constructing the WWW-Authenticate response header, the 'realm' parameter is concatenated without sanitizing Carriage Return (CR) and Line Feed (LF) characters. If an attacker c…
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Medium 5.3
guzzlehttp/psr7 has CRLF Injection via URI Host Component
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Medium 6.3
HTTP Response Splitting via Non-VCHAR Bytes in cow_http_struct_hd:escape_string/2
Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting') vulnerability in ninenines cowlib allows HTTP response splitting via non-VCHAR bytes in structured-fields string values. cow_http_struct_hd:escape_string/2 in cowlib…
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Medium 5.3
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Medium 4.3
Hono: Cookie helper does not sanitize sameSite and priority, allowing Set-Cookie injection
Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, the serialize() function in hono/cookie validates domain and path options against characters that corrupt Set-Cookie header syntax (;, \r, \n), but does no…
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Medium 5.8
eventsource-encoder: SSE event injection via unsanitized event and id fields
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Medium 6.5
HTTP::Tiny versions before 0.093 for Perl do not validate CRLF in HTTP request lines or control field header values
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Medium 5.9
Electron: HTTP Response Header Injection in custom protocol handlers and webRequest
Electron is a framework for writing cross-platform desktop applications using JavaScript, HTML and CSS. Prior to versions 38.8.6, 39.8.3, 40.8.3, and 41.0.3, apps that register custom protocol handlers via protocol.handle() / protocol.registerSchemesAsPrivile…
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Medium 5.3
ewe Has Improper Neutralization of CRLF Sequences in HTTP Headers (HTTP Request/Response Splitting)
ewe is a Gleam web server. Prior to version 3.0.6, the encode_headers function in src/ewe/internal/encoder.gleam directly interpolates response header keys and values into raw HTTP bytes without validating or stripping CRLF (\r\n) sequences. An application th…
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Medium 5.4
Hono: Cookie Attribute Injection via Unsanitized domain and path in setCookie()
Hono is a Web application framework that provides support for any JavaScript runtime. Prior to version 4.12.4, the setCookie() utility did not validate semicolons (;), carriage returns (\r), or newline characters (\n) in the domain and path options when const…
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Medium 6.4
calibre Vulnerable to HTTP Response Header Injection
calibre is a cross-platform e-book manager for viewing, converting, editing, and cataloging e-books. Prior to version 9.4.0, an HTTP Response Header Injection vulnerability in the calibre Content Server allows any authenticated user to inject arbitrary HTTP h…
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Medium 5.3
Gakido vulnerable to HTTP Header Injection (CRLF Injection)
Gakido is a Python HTTP client focused on browser impersonation and anti-bot evasion. A vulnerability was discovered in Gakido prior to version 0.1.1 that allowed HTTP header injection through CRLF (Carriage Return Line Feed) sequences in user-supplied header…
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Medium 6.3
BlackSheep ClientSession is vulnerable to CRLF injection
BlackSheep is an asynchronous web framework to build event based web applications with Python. Prior to 2.4.6, the HTTP Client implementation in BlackSheep is vulnerable to CRLF injection. Missing headers validation makes it possible for an attacker to modify…
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Medium 4.3
CRLF Injection vulnerability in SAP S/4HANA (Supplier invoice)
SAP S/4HANA Supplier invoice is vulnerable to CRLF Injection. An attacker with user-level privileges can bypass the allowlist and insert untrusted sites into the 'Trusted Sites' configuration by injecting line feed (LF) characters into application inputs. Thi…
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Medium 6.5
RFD Attack via “Content-Disposition” Header Sourced from Request
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Medium 4.3
Pitchfork HTTP Request/Response Splitting vulnerability
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Medium 5.9
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Medium 6.9
CRLF injection in Cpp-httplib
cpp-httplib version v0.17.3 through v0.18.3 fails to filter CRLF characters ("\r\n") when those are prefixed with a null byte. This enables attackers to exploit CRLF injection that could further lead to HTTP Response Splitting, XSS, and more.
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Medium 6.4
An Improper Neutralization of CRLF Sequences in HTTP Headers ('http response splitting') vulnerability [CWE-113] in For…
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Medium 6.1
CRLF Injection in RestSharp's `RestRequest.AddHeader` method
RestSharp is a Simple REST and HTTP API Client for .NET. The second argument to `RestRequest.AddHeader` (the header value) is vulnerable to CRLF injection. The same applies to `RestRequest.AddOrUpdateHeader` and `RestClient.AddDefaultHeader`. The way HTTP hea…