PT-2026-29817 · Rack+3 · Rack+3

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CVE-2026-34829

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Published

2026-04-02

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Updated

2026-06-22

CVSS v2.0

7.8

High

VectorAV:N/AC:L/Au:N/C:N/I:N/A:C
Name of the Vulnerable Software and Affected Versions Rack versions prior to 2.2.23, 3.1.21, and 3.2.6
Description Rack's Rack::Multipart::Parser does not limit the size of multipart uploads when a Content-Length header is not present, such as with HTTP chunked transfer encoding. Specifically, when processing multipart/form-data requests without a Content-Length header, the parser continues reading until the end of the stream without a size limit. For file parts, the uploaded data is written directly to a temporary file without being constrained by the in-memory upload limit. This allows an unauthenticated attacker to stream an arbitrarily large file upload, potentially consuming unbounded disk space and causing a denial of service. The parser applies BoundedIO only when content length is not nil:
ruby
io = BoundedIO.new(io, content length) if content length
Recommendations Update to Rack version 2.2.23 or later. Update to Rack version 3.1.21 or later. Update to Rack version 3.2.6 or later.

Exploit

Fix

DoS

Resource Exhaustion

Allocation of Resources Without Limits

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Weakness Enumeration

Related Identifiers

BDU:2026-07729
CVE-2026-34829
GHSA-8VQR-QJWX-82MW
OPENSUSE-SU-2026:10508-1
SUSE-SU-2026:1745-1
SUSE-SU-2026:1964-1
SUSE-SU-2026:2487-1
USN-8182-1

Affected Products

Linuxmint
Rack
Red Os
Ubuntu