Upstream information
Description
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
SUSE information
Overall state of this security issue: Resolved
This issue is currently rated as having critical severity.
| CVSS detail | CNA (openjs) | National Vulnerability Database |
|---|---|---|
| Base Score | 6.5 | 9.8 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Attack Vector | Network | Network |
| Attack Complexity | Low | Low |
| Privileges Required | None | None |
| User Interaction | None | None |
| Scope | Unchanged | Unchanged |
| Confidentiality Impact | None | High |
| Integrity Impact | Low | High |
| Availability Impact | Low | High |
| CVSSv3 Version | 3.1 | 3.1 |
SUSE Security Advisories:
- RHSA-2026:7123, published Thu Apr 9 15:08:10 UTC 2026
List of released packages
| Product(s) | Fixed package version(s) | References |
|---|---|---|
| SUSE Liberty Linux 8 |
| Patchnames: RHSA-2026:7123 |
SUSE Timeline for this CVE
CVE page created: Thu Mar 12 22:03:32 2026CVE page last modified: Thu Apr 9 20:44:35 2026