GHSA-6xw4-3v39-52mm

Suggest an improvement
Source
https://github.com/advisories/GHSA-6xw4-3v39-52mm
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/10/GHSA-6xw4-3v39-52mm/GHSA-6xw4-3v39-52mm.json
JSON Data
https://api.test.osv.dev/v1/vulns/GHSA-6xw4-3v39-52mm
Aliases
Downstream
Related
Published
2025-10-10T17:33:35Z
Modified
2025-10-15T07:32:18.474919Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
Rack is vulnerable to a memory-exhaustion DoS through unbounded URL-encoded body parsing
Details

Summary

Rack::Request#POST reads the entire request body into memory for Content-Type: application/x-www-form-urlencoded, calling rack.input.read(nil) without enforcing a length or cap. Large request bodies can therefore be buffered completely into process memory before parsing, leading to denial of service (DoS) through memory exhaustion.

Details

When handling non-multipart form submissions, Rack’s request parser performs:

form_vars = get_header(RACK_INPUT).read

Since read is called with no argument, the entire request body is loaded into a Ruby String. This occurs before query parameter parsing or enforcement of any params_limit. As a result, Rack applications without an upstream body-size limit can experience unbounded memory allocation proportional to request size.

Impact

Attackers can send large application/x-www-form-urlencoded bodies to consume process memory, causing slowdowns or termination by the operating system (OOM). The effect scales linearly with request size and concurrency. Even with parsing limits configured, the issue occurs before those limits are enforced.

Mitigation

  • Update to a patched version of Rack that enforces form parameter limits using query_parser.bytesize_limit, preventing unbounded reads of application/x-www-form-urlencoded bodies.
  • Enforce strict maximum body size at the proxy or web server layer (e.g., Nginx client_max_body_size, Apache LimitRequestBody).
Database specific 
{
    "severity": "HIGH",
    "cwe_ids": [
        "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-10-10T17:33:35Z",
    "nvd_published_at": "2025-10-10T20:15:37Z"
}
References

Affected packages

RubyGems / rack

Package

Name
rack
Purl
pkg:gem/rack

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
2.2.20

Affected versions

0.*

0.1.0
0.2.0
0.3.0
0.4.0
0.9.0
0.9.1

1.*

1.0.0
1.0.1
1.1.0
1.1.1.pre
1.1.1
1.1.2
1.1.3
1.1.4
1.1.5
1.1.6
1.2.0
1.2.1
1.2.2
1.2.3
1.2.4
1.2.5
1.2.6
1.2.7
1.2.8
1.3.0.beta
1.3.0.beta2
1.3.0
1.3.1
1.3.2
1.3.3
1.3.4
1.3.5
1.3.6
1.3.7
1.3.8
1.3.9
1.3.10
1.4.0
1.4.1
1.4.2
1.4.3
1.4.4
1.4.5
1.4.6
1.4.7
1.5.0.beta.1
1.5.0.beta.2
1.5.0
1.5.1
1.5.2
1.5.3
1.5.4
1.5.5
1.6.0.beta
1.6.0.beta2
1.6.0
1.6.1
1.6.2
1.6.3
1.6.4
1.6.5
1.6.6
1.6.7
1.6.8
1.6.9
1.6.10
1.6.11
1.6.12
1.6.13

2.*

2.0.0.alpha
2.0.0.rc1
2.0.1
2.0.2
2.0.3
2.0.4
2.0.5
2.0.6
2.0.7
2.0.8
2.0.9
2.0.9.1
2.0.9.2
2.0.9.3
2.0.9.4
2.1.0
2.1.1
2.1.2
2.1.3
2.1.4
2.1.4.1
2.1.4.2
2.1.4.3
2.1.4.4
2.2.0
2.2.1
2.2.2
2.2.3
2.2.3.1
2.2.4
2.2.5
2.2.6
2.2.6.1
2.2.6.2
2.2.6.3
2.2.6.4
2.2.7
2.2.8
2.2.8.1
2.2.9
2.2.10
2.2.11
2.2.12
2.2.13
2.2.14
2.2.15
2.2.16
2.2.17
2.2.18
2.2.19

RubyGems / rack

Package

Name
rack
Purl
pkg:gem/rack

Affected ranges

Type
ECOSYSTEM
Events
Introduced
3.0
Fixed
3.1.18

Affected versions

3.*

3.0.0
3.0.1
3.0.2
3.0.3
3.0.4
3.0.4.1
3.0.4.2
3.0.5
3.0.6
3.0.6.1
3.0.7
3.0.8
3.0.9
3.0.9.1
3.0.10
3.0.11
3.0.12
3.0.13
3.0.14
3.0.15
3.0.16
3.0.17
3.0.18
3.1.0
3.1.1
3.1.2
3.1.3
3.1.4
3.1.5
3.1.6
3.1.7
3.1.8
3.1.9
3.1.10
3.1.11
3.1.12
3.1.13
3.1.14
3.1.15
3.1.16
3.1.17

RubyGems / rack

Package

Name
rack
Purl
pkg:gem/rack

Affected ranges

Type
ECOSYSTEM
Events
Introduced
3.2
Fixed
3.2.3

Affected versions

3.*

3.2.0
3.2.1
3.2.2