SecuriTricks - CVE-2026-1525

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

Product(s) Impacted

Vendor	Product	Versions
Undici	Undici	*

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-444

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

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.

*CPE(s)

Affected systems and software identified for this CVE.

Type	Vendor	Product	Version	Update	Edition	Language	Software Edition	Target Software	Target Hardware	Other Information
a	undici	undici	/	/	/	/	/	/	/	/

References

https://cna.openjsf.org/security-advisories.html

https://cwe.mitre.org/data/definitions/444.html

https://github.com/nodejs/undici/security/advisories/GHSA-2mjp-6q6p-2qxm

https://hackerone.com/reports/3556037

https://www.rfc-editor.org/rfc/rfc9110.html#section-8.6

CVSS Score

6.5 / 10

CVSS Data - 3.1

Attack Vector: NETWORK
Attack Complexity: LOW
Privileges Required: NONE
Scope: UNCHANGED
Confidentiality Impact: NONE
Integrity Impact: LOW
Availability Impact: LOW

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

View Vector String

Timeline

Published: March 12, 2026, 8:16 p.m.
Last Modified: March 12, 2026, 9:07 p.m.

Status : Awaiting Analysis

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

ce714d77-add3-4f53-aff5-83d477b104bb

CVE-2026-1525