undicis retry interceptor can append the body of a ranged retry response to bytes already delivered from an earlier partial response while still presenting the original responses status and headers. This happens when an upstream server delivers part of a body without a trustworthy resume checkpoint, for example a non-success response whose headers were already sent or a partial-content response with an unusable content range, then closes the connection and answers the resumed range request with more bytes. As a result the response body can be longer than the Content-Length that the application observes. An application that relays such a response to a downstream HTTP/1.1 peer without normalizing the framing can emit a body that exceeds the forwarded Content-Length, and the excess bytes can be interpreted as the start of a following response, which enables downstream response splitting or desynchronization. Exploitation requires an attacker-controlled upstream server and an application that forwards the response through a framing-sensitive path. This affects undici versions before 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.
Weakness
The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Undici | Nodejs | * | 6.28.1 (excluding) |
| Undici | Nodejs | 7.0.0 (including) | 7.29.1 (excluding) |
| Undici | Nodejs | 8.0.0 (including) | 8.10.2 (excluding) |
| Red Hat Hardened Images | RedHat | grafana12-4-main-12.4.10-0.2.hum1 | * |
| Red Hat Hardened Images | RedHat | nodejs26-main-11.19.1-1.26.8.2.0.1.hum1 | * |
| Red Hat Hardened Images | RedHat | nodejs26-main-26.8.2-0.1.hum1 | * |
| Red Hat Hardened Images | RedHat | nodejs24-main-11.19.0-1.24.21.0.1.hum1 | * |
| Red Hat Hardened Images | RedHat | nodejs24-main-24.21.0-1.hum1 | * |
| Node-undici | Ubuntu | upstream | * |
Extended Description
HTTP requests or responses (“messages”) can be malformed or unexpected in ways that cause web servers or clients to interpret the messages in different ways than intermediary HTTP agents such as load balancers, reverse proxies, web caching proxies, application firewalls, etc. For example, an adversary may be able to add duplicate or different header fields that a client or server might interpret as one set of messages, whereas the intermediary might interpret the same sequence of bytes as a different set of messages. For example, discrepancies can arise in how to handle duplicate headers like two Transfer-encoding (TE) or two Content-length (CL), or the malicious HTTP message will have different headers for TE and CL. The inconsistent parsing and interpretation of messages can allow the adversary to “smuggle” a message to the client/server without the intermediary being aware of it. This weakness is usually the result of the usage of outdated or incompatible HTTP protocol versions in the HTTP agents.