REDHAT-BUG-2447144: Medium severity npm/undici vulnerability
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
Affected Software
Event History
Frequently Asked Questions
What is the severity of REDHAT-BUG-2447144?
The severity of REDHAT-BUG-2447144 is classified as medium with a score of 4.
How do I fix REDHAT-BUG-2447144?
To fix REDHAT-BUG-2447144, ensure that the application using undici does not send duplicate Content-Length headers with case-variant names.
What applications are impacted by REDHAT-BUG-2447144?
Applications that use the npm/undici library are impacted by REDHAT-BUG-2447144.
What is the main issue described in REDHAT-BUG-2447144?
The main issue in REDHAT-BUG-2447144 is that undici allows duplicate HTTP Content-Length headers, resulting in malformed HTTP/1.1 requests.
When was REDHAT-BUG-2447144 published?
REDHAT-BUG-2447144 was published on March 12, 2026.