CVE-2020-5249: Puma HTTP Response Splitting (Early Hints) Vulnerability
MODERATECVE-2020-5249 is a MODERATE (CVSS 6.5) http response splitting (early hints) vulnerability (CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')) affecting Puma libraries in the RubyGems ecosystem. The issue involves http response splitting (early hints) in puma. Remediation is available by upgrading affected packages to version 3.12.4, 4.3.3.
CVE-2020-5249 at a Glance
Security Impact
CVSS: 6.5
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L).
How to Fix CVE-2020-5249
To remediate this vulnerability, upgrade all affected Puma dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade puma to 3.12.4Upgrade puma to 4.3.3Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for pumaHow to Check if You Are Affected
To determine whether your application is affected by CVE-2020-5249, inspect your project dependencies for Puma:
inspect dependencies for pumaAnalyze the terminal output to locate any version of Puma in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.12.4), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting'), where the product receives data from an http agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes cr and lf characters before the data is included in outgoing http headers. In Puma, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2020-5249 Affected Puma Versions
2 component(s)References
Frequently Asked Questions
What is CVE-2020-5249?
Which Puma versions are affected?
What version fixes CVE-2020-5249?
Is puma affected?
What is the CVSS score of CVE-2020-5249?
What CWE is associated with CVE-2020-5249?
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Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-33vf-4xgg-9r58",
"modified" : "2023-05-16T16:16:20Z",
"published" : "2020-03-03T23:33:16Z",
"aliases" : [ "CVE-2020-5249" ],
"summary" : "HTTP Response Splitting (Early Hints) in Puma",
"details" : "### Impact\nIf an application using Puma allows untrusted input in an early-hints header, an attacker can use a carriage return character to end the header and inject malicious content, such as additional headers or an entirely new response body. This vulnerability is known as [HTTP Response Splitting](https://owasp.org/www-community/attacks/HTTP_Response_Splitting).\n\nWhile not an attack in itself, response splitting is a vector for several other attacks, such as cross-site scripting (XSS).\n\nThis is related to [CVE-2020-5247](https://github.com/puma/puma/security/advisories/GHSA-84j7-475p-hp8v), which fixed this vulnerability but only for regular responses.\n\n### Patches\nThis has been fixed in 4.3.3 and 3.12.4.\n\n### Workarounds\nUsers can not allow untrusted/user input in the Early Hints response header.\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [puma](https://github.com/puma/puma)\n* Email us a project maintainer. [Email addresses are listed in our Code of Conduct](https://github.com/puma/puma/blob/master/CODE_OF_CONDUCT.md#enforcement).",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "RubyGems",
"name" : "puma"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "3.12.4"
} ]
} ]
}, {
"package" : {
"ecosystem" : "RubyGems",
"name" : "puma"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "4.0.0"
}, {
"fixed" : "4.3.3"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/puma/puma/security/advisories/GHSA-33vf-4xgg-9r58"
}, {
"type" : "WEB",
"url" : "https://github.com/puma/puma/security/advisories/GHSA-84j7-475p-hp8v"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-5249"
}, {
"type" : "WEB",
"url" : "https://github.com/puma/puma/commit/c22712fc93284a45a93f9ad7023888f3a65524f3"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/puma/puma"
}, {
"type" : "WEB",
"url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/puma/CVE-2020-5249.yml"
}, {
"type" : "WEB",
"url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/BMJ3CGZ3DLBJ5WUUKMI5ZFXFJQMXJZIK"
}, {
"type" : "WEB",
"url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/DIHVO3CQMU7BZC7FCTSRJ33YDNS3GFPK"
}, {
"type" : "WEB",
"url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/NJ3LL5F5QADB6LM46GXZETREAKZMQNRD"
}, {
"type" : "WEB",
"url" : "https://owasp.org/www-community/attacks/HTTP_Response_Splitting"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-113", "CWE-74" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2020-03-02T15:03:13Z",
"nvd_published_at" : "2020-03-02T16:15:12Z"
}
}