Описание
Undici has an HTTP Request/Response Smuggling issue
Impact
Undici allows duplicate HTTP Content-Length headers when they are provided in an array with case-variant names (e.g., Content-Length and content-length). This produces malformed HTTP/1.1 requests with multiple conflicting Content-Length values on the wire.
Who is impacted:
- Applications using
undici.request(),undici.Client, or similar low-level APIs with headers passed as flat arrays - Applications that accept user-controlled header names without case-normalization
Potential consequences:
- Denial of Service: Strict HTTP parsers (proxies, servers) will reject requests with duplicate
Content-Lengthheaders (400 Bad Request) - HTTP Request Smuggling: In deployments where an intermediary and backend interpret duplicate headers inconsistently (e.g., one uses the first value, the other uses the last), this can enable request smuggling attacks leading to ACL bypass, cache poisoning, or credential hijacking
Patches
Patched in the undici version v7.24.0 and v6.24.0. Users should upgrade to this version or later.
Workarounds
If upgrading is not immediately possible:
- Validate header names: Ensure no duplicate
Content-Lengthheaders (case-insensitive) are present before passing headers to undici - Use object format: Pass headers as a plain object (
{ 'content-length': '123' }) rather than an array, which naturally deduplicates by key - Sanitize user input: If headers originate from user input, normalize header names to lowercase and reject duplicates
Ссылки
- https://github.com/nodejs/undici/security/advisories/GHSA-2mjp-6q6p-2qxm
- https://nvd.nist.gov/vuln/detail/CVE-2026-1525
- https://hackerone.com/reports/3556037
- https://cna.openjsf.org/security-advisories.html
- https://cwe.mitre.org/data/definitions/444.html
- https://www.rfc-editor.org/rfc/rfc9110.html#section-8.6
Пакеты
undici
< 6.24.0
6.24.0
undici
>= 7.0.0, < 7.24.0
7.24.0
Связанные уязвимости
Undici allows duplicate HTTP Content-Length headers when they are provided in an array with case-variant names (e.g., Content-Length and content-length). This produces malformed HTTP/1.1 requests with multiple conflicting Content-Length values on the wire. Who is impacted: * Applications using undici.request(), undici.Client, or similar low-level APIs with headers passed as flat arrays * Applications that accept user-controlled header names without case-normalization Potential consequences: * Denial of Service: Strict HTTP parsers (proxies, servers) will reject requests with duplicate Content-Length headers (400 Bad Request) * HTTP Request Smuggling: In deployments where an intermediary and backend interpret duplicate headers inconsistently (e.g., one uses the first value, the other uses the last), this can enable request smuggling attacks leading to ACL bypass, cache poisoning, or credential hijacking
A flaw was found in undici, a Node.js HTTP/1.1 client. A remote attacker could exploit this vulnerability by sending HTTP/1.1 requests that include duplicate Content-Length headers with different casing (e.g., "Content-Length" and "content-length"). This can lead to HTTP Request Smuggling, a technique where an attacker sends an ambiguous request that is interpreted differently by a proxy and a backend server. Successful exploitation could result in unauthorized access, cache poisoning, or credential hijacking. It may also cause a Denial of Service (DoS) if strict HTTP parsers reject the malformed requests.
Undici allows duplicate HTTP Content-Length headers when they are provided in an array with case-variant names (e.g., Content-Length and content-length). This produces malformed HTTP/1.1 requests with multiple conflicting Content-Length values on the wire. Who is impacted: * Applications using undici.request(), undici.Client, or similar low-level APIs with headers passed as flat arrays * Applications that accept user-controlled header names without case-normalization Potential consequences: * Denial of Service: Strict HTTP parsers (proxies, servers) will reject requests with duplicate Content-Length headers (400 Bad Request) * HTTP Request Smuggling: In deployments where an intermediary and backend interpret duplicate headers inconsistently (e.g., one uses the first value, the other uses the last), this can enable request smuggling attacks leading to ACL bypass, cache poisoning, or credential hijacking
Undici allows duplicate HTTPContent-Lengthheaders when they are provid ...