CVE-2026-34831
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Summary
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.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| rack | rack | < 2.2.23 | affected |
| rack | rack | >= 3.0.0.beta1, < 3.1.21 | affected |
| rack | rack | >= 3.2.0, < 3.2.6 | affected |
Weaknesses
- CWE-130: CWE-130: Improper Handling of Length Parameter Inconsistency
- CWE-135: CWE-135: Incorrect Calculation of Multi-Byte String Length
ADP Enrichment
CISA ADP Vulnrichment
- SSVC:
- Exploitation: none
- Automatable: no
- Technical Impact: partial
References
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