CVE-2026-34831
Essential information
- Published
- 02/04/2026 17:16
- Modified
- 03/04/2026 16:10
- Author
- —
- Creator
- —
- CVSS
- 4.8 MEDIUM (v3.1)
- CISA KEV
- No
- CWE
- —
- CVSS vector
-
—
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N—
CVSS metrics
- Access vector
- —
- Access complexity
- —
- Authentication
- —
- Confidentiality impact
- —
- Integrity impact
- —
- Availability impact
- —
- Exploitability
- —
- Remediation level
- —
- Report confidence
- —
- Temporal score
- —
- Attack vector
- NETWORK
- Attack complexity
- HIGH
- Privileges required
- NONE
- User interaction
- NONE
- Scope
- UNCHANGED
- Confidentiality impact
- LOW
- Integrity impact
- LOW
- Availability impact
- NONE
- Exploit code maturity
- —
- Remediation level
- —
- Report confidence
- —
- Temporal score
- —
- Attack vector
- —
- Attack complexity
- —
- Attack requirements
- —
- Privileges required
- —
- User interaction
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- Confidentiality (V)
- —
- Confidentiality (S)
- —
- Integrity (V)
- —
- Integrity (S)
- —
- Availability (V)
- —
- Availability (S)
- —
- Exploit maturity
- —
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.
NVD status
- Status
- Undergoing Analysis — CVE has been recently published to the CVE List and has been received by the NVD.
- Source
- [email protected]
- NVD
- View on NVD
Affected products (CPE)
| Product | CPE |
|---|---|
| ruby / rack | cpe:2.3:a:ruby:rack:<2.2.23:*:*:*:*:*:*:* |
| ruby / rack | cpe:2.3:a:ruby:rack:<3.1.21:*:*:*:*:*:*:* |
| ruby / rack | cpe:2.3:a:ruby:rack:<3.2.6:*:*:*:*:*:*:* |