FKIE_CVE-2026-42256
Vulnerability from fkie_nvd - Published: 2026-05-09 20:16 - Updated: 2026-07-24 19:10
Severity
Summary
Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. From versions 0.4.0 to before 0.4.24, 0.5.0 to before 0.5.14, and 0.6.0 to before 0.6.4, when authenticating a connection with SCRAM-SHA1 or SCRAM-SHA256, a hostile server can perform a computational denial-of-service attack on the client process by sending a big iteration count value. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.
References
{
"affected": [
{
"affectedData": [
{
"product": "net-imap",
"vendor": "ruby",
"versions": [
{
"status": "affected",
"version": "\u003e= 0.4.0, \u003c 0.4.24"
},
{
"status": "affected",
"version": "\u003e= 0.5.0, \u003c 0.5.14"
},
{
"status": "affected",
"version": "\u003e= 0.6.0, \u003c 0.6.4"
}
]
}
],
"source": "security-advisories@github.com"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:ruby-lang:net\\:\\:imap:*:*:*:*:*:ruby:*:*",
"matchCriteriaId": "79EE9345-B825-40F9-9CFF-9E9E1A3783DD",
"versionEndExcluding": "0.4.24",
"versionStartIncluding": "0.4.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:ruby-lang:net\\:\\:imap:*:*:*:*:*:ruby:*:*",
"matchCriteriaId": "2CCEB891-1D8F-4431-A79C-2A7560A84F4E",
"versionEndExcluding": "0.5.14",
"versionStartIncluding": "0.5.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:ruby-lang:net\\:\\:imap:*:*:*:*:*:ruby:*:*",
"matchCriteriaId": "9A6D1995-BFA3-490F-967D-252CA7BE2264",
"versionEndExcluding": "0.6.4",
"versionStartIncluding": "0.6.0",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. From versions 0.4.0 to before 0.4.24, 0.5.0 to before 0.5.14, and 0.6.0 to before 0.6.4, when authenticating a connection with SCRAM-SHA1 or SCRAM-SHA256, a hostile server can perform a computational denial-of-service attack on the client process by sending a big iteration count value. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4."
},
{
"lang": "es",
"value": "Net::IMAP implementa la funcionalidad de cliente del Protocolo de Acceso a Mensajes de Internet (IMAP) en Ruby. Desde las versiones 0.4.0 hasta antes de la 0.4.24, 0.5.0 hasta antes de la 0.5.14, y 0.6.0 hasta antes de la 0.6.4, al autenticar una conexi\u00f3n con SCRAM-SHA1 o SCRAM-SHA256, un servidor hostil puede realizar un ataque de denegaci\u00f3n de servicio computacional en el proceso del cliente al enviar un valor de recuento de iteraciones grande. Este problema ha sido parcheado en las versiones 0.4.24, 0.5.14 y 0.6.4."
}
],
"id": "CVE-2026-42256",
"lastModified": "2026-07-24T19:10:00.160",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 6.5,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 2.8,
"impactScore": 3.6,
"source": "nvd@nist.gov",
"type": "Primary"
}
],
"cvssMetricV40": [
{
"cvssData": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "NETWORK",
"availabilityRequirement": "NOT_DEFINED",
"baseScore": 6.0,
"baseSeverity": "MEDIUM",
"confidentialityRequirement": "NOT_DEFINED",
"exploitMaturity": "NOT_DEFINED",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedSubIntegrityImpact": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnIntegrityImpact": "NOT_DEFINED",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "PASSIVE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"version": "4.0",
"vulnAvailabilityImpact": "HIGH",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"source": "security-advisories@github.com",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-42256",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-05-11T17:04:26.784816Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-05-09T20:16:28.313",
"references": [
{
"source": "security-advisories@github.com",
"tags": [
"Patch"
],
"url": "https://github.com/ruby/net-imap/commit/158d0b505074397cdb5ceb58935e42dd2bcfa612"
},
{
"source": "security-advisories@github.com",
"tags": [
"Patch"
],
"url": "https://github.com/ruby/net-imap/commit/808001bc45c06f7297a7e96d341279e041a7f7f4"
},
{
"source": "security-advisories@github.com",
"tags": [
"Patch"
],
"url": "https://github.com/ruby/net-imap/commit/99f59eab6064955a23debd95410263ad144df758"
},
{
"source": "security-advisories@github.com",
"tags": [
"Release Notes"
],
"url": "https://github.com/ruby/net-imap/releases/tag/v0.4.24"
},
{
"source": "security-advisories@github.com",
"tags": [
"Release Notes"
],
"url": "https://github.com/ruby/net-imap/releases/tag/v0.5.14"
},
{
"source": "security-advisories@github.com",
"tags": [
"Release Notes"
],
"url": "https://github.com/ruby/net-imap/releases/tag/v0.6.4"
},
{
"source": "security-advisories@github.com",
"tags": [
"Mitigation",
"Vendor Advisory"
],
"url": "https://github.com/ruby/net-imap/security/advisories/GHSA-87pf-fpwv-p7m7"
}
],
"sourceIdentifier": "security-advisories@github.com",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-770"
},
{
"lang": "en",
"value": "CWE-1322"
}
],
"source": "security-advisories@github.com",
"type": "Secondary"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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