CVE-2025-6442CWE-444

Ruby WEBrick read_header HTTP Request Smuggling Vulnerability

Medium · published June 25, 2025

CVSS v3.0
6.5
EPSS
0%
Percentile
41.5
In the wild
Unconfirmed
What it is

Ruby WEBrick read_header HTTP Request Smuggling Vulnerability. This vulnerability allows remote attackers to smuggle arbitrary HTTP requests on affected installations of Ruby WEBrick. This issue is exploitable when the product is deployed behind an HTTP proxy that fulfills specific conditions.

The specific flaw exists within the read_headers method. The issue results from the inconsistent parsing of terminators of HTTP headers. An attacker can leverage this vulnerability to smuggle arbitrary HTTP requests. Was ZDI-CAN-21876.

The record
Technical detail
CVSS v3.0
6.5 · MEDIUM
Vector
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00495 · 41.5th percentile
Weakness
CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Published
2025-06-25T16:52Z
EPSS history
Timeline
  • 25 JUN 16:52Z
    Ruby WEBrick read_header HTTP Request Smuggling Vulnerability
    cvelistv5