CVE-2026-34827

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Source
https://cve.org/CVERecord?id=CVE-2026-34827
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-34827.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-34827
Aliases
Downstream
Related
Published
2026-04-02T17:07:48.279Z
Modified
2026-04-06T00:44:18.906605415Z
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: Algorithmic-Complexity DoS in Rack::Multipart::Parser
Details

Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21, and 3.2.0 to before 3.2.6, Rack::Multipart::Parser#handlemimehead parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated String#index searches combined with String#slice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An unauthenticated attacker can send a crafted multipart/form-data request containing many parts with long backslash-escaped parameter values to trigger excessive CPU usage during multipart parsing. This results in a denial of service condition in Rack applications that accept multipart form data. This issue has been patched in versions 3.1.21 and 3.2.6.

Database specific 
{
    "cwe_ids": [
        "CWE-400",
        "CWE-407",
        "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34827.json",
    "cna_assigner": "GitHub_M"
}
References

Affected packages

Git / github.com/rack/rack

Affected ranges

Type
GIT
Repo
https://github.com/rack/rack
Events
Introduced
572a42a705b423ce98ef4e81435d4f60fb0ae53d
Fixed
ae8431120e66e92d1885ab8ec0a553d9cad5ec13
Database specific 
{
    "versions": [
        {
            "introduced": "3.0.0.beta1"
        },
        {
            "fixed": "3.1.21"
        }
    ]
}
Type
GIT
Repo
https://github.com/rack/rack
Events
Introduced
b68251c03788ff39d4a4b25424df7360426e4afd
Fixed
e1f22fdbe99afd2126b6fbf05bb12399359574b7
Database specific 
{
    "versions": [
        {
            "introduced": "3.2.0"
        },
        {
            "fixed": "3.2.6"
        }
    ]
}

Affected versions

3.*
3.0.0
3.0.0.beta1
3.0.0.rc1
v3.*
v3.0.1
v3.0.10
v3.0.12
v3.0.13
v3.0.14
v3.0.15
v3.0.16
v3.0.17
v3.0.18
v3.0.2
v3.0.3
v3.0.4
v3.0.4.1
v3.0.4.2
v3.0.5
v3.0.6
v3.0.6.1
v3.0.7
v3.0.8
v3.0.9
v3.0.9.1
v3.1.0
v3.1.1
v3.1.10
v3.1.11
v3.1.12
v3.1.13
v3.1.14
v3.1.15
v3.1.16
v3.1.17
v3.1.18
v3.1.19
v3.1.2
v3.1.20
v3.1.3
v3.1.4
v3.1.5
v3.1.6
v3.1.7
v3.1.8
v3.1.9
v3.2.0
v3.2.1
v3.2.2
v3.2.3
v3.2.4
v3.2.5
v3.2.6

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-34827.json"