CVE-2026-34831
April 3, 2026, 4:10 p.m.
4.8
Medium
Description
Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Files#fail sets the Content-Length response header using String#size instead of String#bytesize. When the response body contains multibyte UTF-8 characters, the declared Content-Length is smaller than the number of bytes actually sent on the wire. Because Rack::Files reflects the requested path in 404 responses, an attacker can trigger this mismatch by requesting a non-existent path containing percent-encoded UTF-8 characters. This results in incorrect HTTP response framing and may cause response desynchronization in deployments that rely on the incorrect Content-Length value. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.
Product(s) Impacted
| Vendor | Product | Versions |
|---|---|---|
| Ruby |
|
|
Weaknesses
Common security weaknesses mapped to this vulnerability.
CWE-130
Improper Handling of Length Parameter Inconsistency
The product parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data.
*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 | ruby | rack | <2.2.23 | / | / | / | / | / | / | / |
| a | ruby | rack | <3.1.21 | / | / | / | / | / | / | / |
| a | ruby | rack | <3.2.6 | / | / | / | / | / | / | / |
Tags
CVSS Score
CVSS Data - 3.1
- Attack Vector: NETWORK
- Attack Complexity: HIGH
- Privileges Required: NONE
- Scope: UNCHANGED
- Confidentiality Impact: LOW
- Integrity Impact: LOW
- Availability Impact: NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Timeline
Published: April 2, 2026, 5:16 p.m.
Last Modified: April 3, 2026, 4:10 p.m.
Last Modified: April 3, 2026, 4:10 p.m.
Status : Undergoing Analysis
CVE has been recently published to the CVE List and has been received by the NVD.
More infoSource
*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.