undici vulnerable to downstream response desynchronization via retry interceptor
undici's retry interceptor can deliver a response whose body length does not match the Content-Length header exposed to the application after a retry or resume of a partial response. In undici before 6.28.0, from 7.0.0 up to before 7.29.0, and from 8.0.0 up to before 8.9.0, a malicious or faulty upstream can return a partial response with a mismatched framing header, close the socket early, and have the retry interceptor assemble a body of a different length while the original Content-Length stays attached. Applications that use the retry interceptor and forward upstream headers and bodies downstream, such as proxies or gateways, may then emi
undici vulnerable to cookie attribute injection via unsanitized domain and unparsed setCookie fields
undici's setCookie function does not fully sanitize cookie attributes. In undici before 6.28.0, from 7.0.0 up to before 7.29.0, and from 8.0.0 up to before 8.9.0, a domain value is not checked for semicolons and entries in the unparsed array are not sanitized, so attacker-influenced input can inject additional cookie attributes. For example, a domain value containing a semicolon can append attributes such as SameSite, and an unparsed entry can inject attributes such as HttpOnly, without the caller setting them. Applications that pass user-controlled input to these fields, such as multi-tenant or reverse-proxy servers that scope session cookie
undici vulnerable to cross-user information disclosure and parse-time crash via degenerate private cache directives
undici's cache interceptor mishandles malformed Cache-Control private directives. In undici 7.0.0 up to before 7.29.0 and 8.0.0 up to before 8.9.0, a response carrying a degenerate qualified private directive, such as private set to an empty value, can be stored in the default shared cache and later served to a different caller with the same cache key, disclosing private response bodies and headers including Set-Cookie. Separately, a Cache-Control header that combines an unqualified private directive with a qualified one triggers an uncaught TypeError in the cache-control parser, which rejects the request and, depending on the consumer's erro
undici vulnerable to Set-Cookie SameSite attribute downgrade via permissive substring matching
Impact:
When undici parses a Set-Cookie header, it accepts any SameSite attribute value that contains Strict, Lax, or None as a substring, rather than the case-insensitive exact match specified by RFC 6265. Non-spec values are silently mapped to one of the three standard tokens. For example, SameSite=NoneOfYourBusiness is parsed as None (the most permissive setting), and SameSite=StrictLax is parsed as Lax (a downgrade from Strict).
Affected applications are those that consume Set-Cookie headers from server responses (for example via undici's fetch or proxy code paths) and then forward or rely on the parsed sameSite attribute. A malicious or
undici vulnerable to HTTP response queue poisoning via keep-alive socket reuse
Impact:
Undici's HTTP/1.1 client is vulnerable to response queue poisoning on reused keep-alive sockets. An attacker-controlled upstream server can inject an unsolicited HTTP/1.1 response onto an idle socket after a request completes. When the client dispatches the next request on that socket, it associates the injected response with the new request, causing responses to be delivered to the wrong requests.
This requires an attacker-controlled or compromised upstream HTTP/1.1 server and keep-alive connection reuse.
Patches:
Upgrade to undici v6.26.0, v7.28.0 or v8.5.0.
Workarounds:
Disable keep-alive connection reuse by setting keepAliveTim
undici WebSocket client vulnerable to denial of service via fragment count bypass
Impact:
The undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service.
Affected applications are those using the undici WebSocket client (new WebSocket(...)) or the WebSocketStream API that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint.
All rele
undici is vulnerable to Unhandled Exception in undici WebSocket Client Due to Invalid server_max_window_bits Validation
ImpactThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range server_max_window_bits value (outside zlib's valid range of 8-15). When the server subsequently sends a compressed frame, the client attempts to create a zlib InflateRaw instance with the invalid windowBits value, causing a synchronous RangeError exception that is not caught, resulting in immediat
Undici has an unbounded decompression chain in HTTP responses on Node.js Fetch API via Content-Encoding leads to resource exhaustion
Undici is an HTTP/1.1 client for Node.js. Prior to 7.18.0 and 6.23.0, the number of links in the decompression chain is unbounded and the default maxHeaderSize allows a malicious server to insert thousands compression steps leading to high CPU usage and excessive memory allocation. This vulnerability is fixed in 7.18.0 and 6.23.0.
A flaw in Node.js 20's HTTP parser allows improper termination of HTTP/1 headers using `\r\n\rX` instead of the required `\r\n\r\n`.
This inconsistency enables request smuggling, allowing attackers to bypass proxy-based access controls and submit unauthorized requests.
The issue was resolved by upgrading `llhttp` to version 9, which enforces correct header termination.
Impact:
* This vulnerability affects only Node.js 20.x users prior to the `llhttp` v9 upgrade.
undici Denial of Service attack via bad certificate data
Undici is an HTTP/1.1 client for Node.js. Prior to versions 5.29.0, 6.21.2, and 7.5.0, applications that use undici to implement a webhook-like system are vulnerable. If the attacker set up a server with an invalid certificate, and they can force the application to call the webhook repeatedly, then they can cause a memory leak. This has been patched in versions 5.29.0, 6.21.2, and 7.5.0. As a workaound, avoid calling a webhook repeatedly if the webhook fails.
Undici is an HTTP/1.1 client. Starting in version 4.5.0 and prior to versions 5.28.5, 6.21.1, and 7.2.3, undici uses `Math.random()` to choose the boundary for a multipart/form-data request. It is known that the output of `Math.random()` can be predicted if several of its generated values are known. If there is a mechanism in an app that sends multipart requests to an attacker-controlled website, they can use this to leak the necessary values. Therefore, an attacker can tamper with the requests going to the backend APIs if certain conditions are met. This is fixed in versions 5.28.5, 6.21.1, and 7.2.3. As a workaround, do not issue multipart
Undici's Proxy-Authorization header not cleared on cross-origin redirect for dispatch, request, stream, pipeline
Undici is an HTTP/1.1 client, written from scratch for Node.js. Undici cleared Authorization and Proxy-Authorization headers for `fetch()`, but did not clear them for `undici.request()`. This vulnerability was patched in version(s) 5.28.4 and 6.11.1.
Undici's fetch with integrity option is too lax when algorithm is specified but hash value is in incorrect
Undici is an HTTP/1.1 client, written from scratch for Node.js. An attacker can alter the `integrity` option passed to `fetch()`, allowing `fetch()` to accept requests as valid even if they have been tampered. This vulnerability was patched in version(s) 5.28.4 and 6.11.1.
Proxy-Authorization header not cleared on cross-origin redirect in fetch in Undici
Undici is an HTTP/1.1 client, written from scratch for Node.js. Undici already cleared Authorization headers on cross-origin redirects, but did not clear `Proxy-Authentication` headers. This issue has been patched in versions 5.28.3 and 6.6.1. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Undici's cookie header not cleared on cross-origin redirect in fetch
Undici is an HTTP/1.1 client written from scratch for Node.js. Prior to version 5.26.2, Undici already cleared Authorization headers on cross-origin redirects, but did not clear `Cookie` headers. By design, `cookie` headers are forbidden request headers, disallowing them to be set in RequestInit.headers in browser environments. Since undici handles headers more liberally than the spec, there was a disconnect from the assumptions the spec made, and undici's implementation of fetch. As such this may lead to accidental leakage of cookie to a third-party site or a malicious attacker who can control the redirection target (ie. an open redirector)
Undici is an HTTP/1.1 client for Node.js. Starting with version 2.0.0 and prior to version 5.19.1, the undici library does not protect `host` HTTP header from CRLF injection vulnerabilities. This issue is patched in Undici v5.19.1. As a workaround, sanitize the `headers.host` string before passing to undici.
Undici vulnerable to Regular Expression Denial of Service in Headers
Undici is an HTTP/1.1 client for Node.js. Prior to version 5.19.1, the `Headers.set()` and `Headers.append()` methods are vulnerable to Regular Expression Denial of Service (ReDoS) attacks when untrusted values are passed into the functions. This is due to the inefficient regular expression used to normalize the values in the `headerValueNormalize()` utility function. This vulnerability was patched in v5.19.1. No known workarounds are available.
CRLF Injection in Nodejs ‘undici’ via Content-Type
undici is an HTTP/1.1 client, written from scratch for Node.js.`=< [email protected]` users are vulnerable to _CRLF Injection_ on headers when using unsanitized input as request headers, more specifically, inside the `content-type` header. Example: ``` import { request } from 'undici' const unsanitizedContentTypeInput = 'application/json\r\n\r\nGET /foo2 HTTP/1.1' await request('http://localhost:3000, { method: 'GET', headers: { 'content-type': unsanitizedContentTypeInput }, }) ``` The above snippet will perform two requests in a single `request` API call: 1) `http://localhost:3000/` 2) `http://localhost:3000/foo2` This issue was patched in Undici
`undici.request` vulnerable to SSRF using absolute URL on `pathname`
undici is an HTTP/1.1 client, written from scratch for Node.js.`undici` is vulnerable to SSRF (Server-side Request Forgery) when an application takes in **user input** into the `path/pathname` option of `undici.request`. If a user specifies a URL such as `http://127.0.0.1` or `//127.0.0.1` ```js const undici = require("undici") undici.request({origin: "http://example.com", pathname: "//127.0.0.1"}) ``` Instead of processing the request as `http://example.org//127.0.0.1` (or `http://example.org/http://127.0.0.1` when `http://127.0.0.1 is used`), it actually processes the request as `http://127.0.0.1/` and sends it to `http://127.0.0.1`. If a d
Uncleared cookies on cross-host/cross-origin redirect in undici
Authorization headers are cleared on cross-origin redirect. However, cookie headers which are sensitive headers and are official headers found in the spec, remain uncleared. There are active users using cookie headers in undici. This may lead to accidental leakage of cookie to a 3rd-party site or a malicious attacker who can control the redirection target (ie. an open redirector) to leak the cookie to the 3rd party site. This was patched in v5.7.1. By default, this vulnerability is not exploitable. Do not enable redirections, i.e. `maxRedirections: 0` (the default).