| Name | CVE-2025-61771 |
| Description | Rack is a modular Ruby web server interface. In versions prior to 2.2.19, 3.1.17, and 3.2.2, ``Rack::Multipart::Parser` stores non-file form fields (parts without a `filename`) entirely in memory as Ruby `String` objects. A single large text field in a multipart/form-data request (hundreds of megabytes or more) can consume equivalent process memory, potentially leading to out-of-memory (OOM) conditions and denial of service (DoS). Attackers can send large non-file fields to trigger excessive memory usage. Impact scales with request size and concurrency, potentially leading to worker crashes or severe garbage-collection overhead. All Rack applications processing multipart form submissions are affected. Versions 2.2.19, 3.1.17, and 3.2.2 enforce a reasonable size cap for non-file fields (e.g., 2 MiB). Workarounds include restricting maximum request body size at the web-server or proxy layer (e.g., Nginx `client_max_body_size`) and validating and rejecting unusually large form fields at the application level. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DLA-4357-1, DSA-6048-1 |
| Debian Bugs | 1117628 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| ruby-rack (PTS) | bullseye | 2.1.4-3+deb11u2 | vulnerable |
| bullseye (security) | 2.1.4-3+deb11u4 | fixed | |
| bookworm | 2.2.13-1~deb12u1 | vulnerable | |
| bookworm (security) | 2.2.20-0+deb12u1 | fixed | |
| trixie | 3.1.16-0.1 | vulnerable | |
| trixie (security) | 3.1.18-1~deb13u1 | fixed | |
| forky, sid | 3.1.18-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| ruby-rack | source | bullseye | 2.1.4-3+deb11u4 | DLA-4357-1 | ||
| ruby-rack | source | bookworm | 2.2.20-0+deb12u1 | DSA-6048-1 | ||
| ruby-rack | source | trixie | 3.1.18-1~deb13u1 | DSA-6048-1 | ||
| ruby-rack | source | (unstable) | 3.1.18-1 | 1117628 |
https://github.com/rack/rack/security/advisories/GHSA-w9pc-fmgc-vxvw
Fixed by: https://github.com/rack/rack/commit/3beacfcd494ec5600c9022d561cfa2f556a524d1 (v3.2.2)
Fixed by: https://github.com/rack/rack/commit/f224f93bb3f16e9b968493fbd7bac751e66d2fdc (v3.1.17)
Fixed by: https://github.com/rack/rack/commit/c370dcd9405a6799763b70a83f06ae2d1aaa0e87 (v2.2.19)