Rack up to 2.2.22/3.1.20/3.2.5 Response Header Rack::Files Content-Length length parameter

CVSS Meta Temp Score
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CTI Interest Score
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5.1$0-$5k0.00

Summaryinfo

A vulnerability was found in Rack up to 2.2.22/3.1.20/3.2.5 and classified as problematic. This impacts the function Rack::Files of the component Response Header Handler. Executing a manipulation of the argument Content-Length can lead to length parameter. This vulnerability is handled as CVE-2026-34831. The attack can be executed remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Rack up to 2.2.22/3.1.20/3.2.5 and classified as problematic. This vulnerability affects the function Rack::Files of the component Response Header Handler. The manipulation of the argument Content-Length with an unknown input leads to a length parameter vulnerability. The CWE definition for the vulnerability is CWE-130. 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. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2026-34831 since 03/30/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 307009 (Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 25.10 : Rack vulnerabilities (USN-8182-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.2.23, 3.1.21 or 3.2.6 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (307009), EUVD (EUVD-2026-18392) and CERT Bund (WID-SEC-2026-1687). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

  • IBM License Metric Tool

Productinfo

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.6
VulDB Meta Temp Score: 5.6

VulDB Base Score: 5.6
VulDB Temp Score: 5.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 6.5
NVD Vector: 🔒

CNA Base Score: 4.8
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Length parameter
CWE: CWE-130 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 307009
Nessus Name: Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 25.10 : Rack vulnerabilities (USN-8182-1)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Rack 2.2.23/3.1.21/3.2.6

Timelineinfo

03/30/2026 CVE reserved
04/02/2026 +3 days Advisory disclosed
04/02/2026 +0 days VulDB entry created
07/26/2026 +115 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-q2ww-5357-x388
Status: Confirmed

CVE: CVE-2026-34831 (🔒)
GCVE (CVE): GCVE-0-2026-34831
GCVE (VulDB): GCVE-100-354946
EUVD: 🔒
CERT Bund: WID-SEC-2026-1687 - IBM License Metric Tool: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff

Entryinfo

Created: 04/02/2026 19:33
Updated: 07/26/2026 15:11
Changes: 04/02/2026 19:33 (65), 04/03/2026 00:36 (1), 04/19/2026 20:42 (2), 05/28/2026 07:36 (7), 07/26/2026 15:11 (10)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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