CVE-2026-81097 (GCVE-0-2026-81097)
Vulnerability from cvelistv5 – Published: 2026-08-27 14:50 – Updated: 2026-08-28 15:59
VLAI
EPSS
VEX
Title
rails-mcp-server 1.4.0 through 1.6.0 OS Command Execution via execute_ruby PTY Escape
Summary
The execute_ruby tool is documented as a read-only Ruby sandbox and is enforced by a pattern denylist together with replacements for the process-spawning methods on Kernel. The pseudo-terminal library's spawn entry points are neither in the denylist nor replaced, so a normal tool call could reach them and start a shell, executing commands as the account running the server and outside the guarded methods. The denylist was introduced with the tool in 1.4.0 and never covered those entry points through 1.6.0. Version 1.6.1 restricts the requires the sandbox permits to a data-only list and blocks dynamic dispatch to execution entry points; 2.0.0 removes the tool.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-27 19:00 UTC
CWE
- CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/maquina-app/rails-mcp-server | product |
| https://github.com/maquina-app/rails-mcp-server/pull/59 | issue-tracking |
| https://github.com/maquina-app/rails-mcp-server/r… | release-notes |
| https://www.vulncheck.com/advisories/rails-mcp-se… | third-party-advisory |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| maquina-app | rails-mcp-server |
Affected:
1.4.0 , ≤ 1.6.0
(semver)
|
guessed |
Date Public
2026-08-26 00:00
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-81097",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-08-27T19:00:31.993065Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-08-28T15:59:55.991Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"collectionURL": "https://github.com/maquina-app/rails-mcp-server",
"defaultStatus": "unaffected",
"packageURL": "pkg:gem/rails-mcp-server",
"product": "rails-mcp-server",
"repo": "https://github.com/maquina-app/rails-mcp-server",
"vendor": "maquina-app",
"versions": [
{
"lessThanOrEqual": "1.6.0",
"status": "affected",
"version": "1.4.0",
"versionType": "semver"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Avishai Gonen (Pluto Security)"
}
],
"datePublic": "2026-08-26T00:00:00.000Z",
"descriptions": [
{
"lang": "en",
"value": "The execute_ruby tool is documented as a read-only Ruby sandbox and is enforced by a pattern denylist together with replacements for the process-spawning methods on Kernel. The pseudo-terminal library\u0027s spawn entry points are neither in the denylist nor replaced, so a normal tool call could reach them and start a shell, executing commands as the account running the server and outside the guarded methods. The denylist was introduced with the tool in 1.4.0 and never covered those entry points through 1.6.0. Version 1.6.1 restricts the requires the sandbox permits to a data-only list and blocks dynamic dispatch to execution entry points; 2.0.0 removes the tool."
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "LOCAL",
"baseScore": 8.6,
"baseSeverity": "HIGH",
"exploitMaturity": "NOT_DEFINED",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "HIGH",
"vulnConfidentialityImpact": "HIGH",
"vulnIntegrityImpact": "HIGH",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
},
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 8.4,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-78",
"description": "Improper Neutralization of Special Elements used in an OS Command (\u0027OS Command Injection\u0027)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-27T14:50:37.617Z",
"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"shortName": "VulnCheck"
},
"references": [
{
"tags": [
"product"
],
"url": "https://github.com/maquina-app/rails-mcp-server"
},
{
"tags": [
"issue-tracking"
],
"url": "https://github.com/maquina-app/rails-mcp-server/pull/59"
},
{
"tags": [
"release-notes"
],
"url": "https://github.com/maquina-app/rails-mcp-server/releases"
},
{
"name": "VulnCheck Advisory: rails-mcp-server 1.4.0 through 1.6.0 OS Command Execution via execute_ruby PTY Escape",
"tags": [
"third-party-advisory"
],
"url": "https://www.vulncheck.com/advisories/rails-mcp-server-1.4.0-through-1.6.0-os-command-execution-via-execute-ruby-pty-escape"
}
],
"source": {
"discovery": "UNKNOWN"
},
"title": "rails-mcp-server 1.4.0 through 1.6.0 OS Command Execution via execute_ruby PTY Escape",
"x_generator": {
"engine": "vulncheck-endgame"
}
}
},
"cveMetadata": {
"assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"assignerShortName": "VulnCheck",
"cveId": "CVE-2026-81097",
"datePublished": "2026-08-27T14:50:37.617Z",
"dateReserved": "2026-08-26T16:00:32.686Z",
"dateUpdated": "2026-08-28T15:59:55.991Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-81097",
"date": "2026-08-28",
"epss": "0.00172",
"percentile": "0.06744"
},
"nvd": "{\"cve\":{\"id\":\"CVE-2026-81097\",\"sourceIdentifier\":\"disclosure@vulncheck.com\",\"published\":\"2026-08-27T17:20:52.110\",\"lastModified\":\"2026-08-27T17:20:52.110\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"The execute_ruby tool is documented as a read-only Ruby sandbox and is enforced by a pattern denylist together with replacements for the process-spawning methods on Kernel. The pseudo-terminal library\u0027s spawn entry points are neither in the denylist nor replaced, so a normal tool call could reach them and start a shell, executing commands as the account running the server and outside the guarded methods. The denylist was introduced with the tool in 1.4.0 and never covered those entry points through 1.6.0. Version 1.6.1 restricts the requires the sandbox permits to a data-only list and blocks dynamic dispatch to execution entry points; 2.0.0 removes the tool.\"}],\"affected\":[{\"source\":\"disclosure@vulncheck.com\",\"affectedData\":[{\"vendor\":\"maquina-app\",\"product\":\"rails-mcp-server\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://github.com/maquina-app/rails-mcp-server\",\"repo\":\"https://github.com/maquina-app/rails-mcp-server\",\"packageURL\":\"pkg:gem/rails-mcp-server\",\"versions\":[{\"version\":\"1.4.0\",\"lessThanOrEqual\":\"1.6.0\",\"versionType\":\"semver\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/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\",\"baseScore\":8.6,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"HIGH\",\"vulnIntegrityImpact\":\"HIGH\",\"vulnAvailabilityImpact\":\"HIGH\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}],\"cvssMetricV31\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":8.4,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.5,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-78\"}]}],\"references\":[{\"url\":\"https://github.com/maquina-app/rails-mcp-server\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://github.com/maquina-app/rails-mcp-server/pull/59\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://github.com/maquina-app/rails-mcp-server/releases\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://www.vulncheck.com/advisories/rails-mcp-server-1.4.0-through-1.6.0-os-command-execution-via-execute-ruby-pty-escape\",\"source\":\"disclosure@vulncheck.com\"}]}}",
"vulnrichment": {
"containers": "{\"cna\": {\"providerMetadata\": {\"orgId\": \"83251b91-4cc7-4094-a5c7-464a1b83ea10\", \"shortName\": \"VulnCheck\", \"dateUpdated\": \"2026-08-27T14:50:37.617Z\"}, \"datePublic\": \"2026-08-26T00:00:00.000Z\", \"title\": \"rails-mcp-server 1.4.0 through 1.6.0 OS Command Execution via execute_ruby PTY Escape\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"The execute_ruby tool is documented as a read-only Ruby sandbox and is enforced by a pattern denylist together with replacements for the process-spawning methods on Kernel. The pseudo-terminal library\u0027s spawn entry points are neither in the denylist nor replaced, so a normal tool call could reach them and start a shell, executing commands as the account running the server and outside the guarded methods. The denylist was introduced with the tool in 1.4.0 and never covered those entry points through 1.6.0. Version 1.6.1 restricts the requires the sandbox permits to a data-only list and blocks dynamic dispatch to execution entry points; 2.0.0 removes the tool.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"cweId\": \"CWE-78\", \"description\": \"Improper Neutralization of Special Elements used in an OS Command (\u0027OS Command Injection\u0027)\", \"type\": \"CWE\"}]}], \"affected\": [{\"vendor\": \"maquina-app\", \"product\": \"rails-mcp-server\", \"collectionURL\": \"https://github.com/maquina-app/rails-mcp-server\", \"repo\": \"https://github.com/maquina-app/rails-mcp-server\", \"defaultStatus\": \"unaffected\", \"versions\": [{\"version\": \"1.4.0\", \"lessThanOrEqual\": \"1.6.0\", \"status\": \"affected\", \"versionType\": \"semver\"}], \"packageURL\": \"pkg:gem/rails-mcp-server\"}], \"metrics\": [{\"format\": \"CVSS\", \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}], \"cvssV4_0\": {\"attackVector\": \"LOCAL\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"NONE\", \"privilegesRequired\": \"NONE\", \"userInteraction\": \"NONE\", \"vulnConfidentialityImpact\": \"HIGH\", \"subConfidentialityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"HIGH\", \"subIntegrityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"HIGH\", \"subAvailabilityImpact\": \"NONE\", \"exploitMaturity\": \"NOT_DEFINED\", \"Safety\": \"NOT_DEFINED\", \"Automatable\": \"NOT_DEFINED\", \"Recovery\": \"NOT_DEFINED\", \"valueDensity\": \"NOT_DEFINED\", \"vulnerabilityResponseEffort\": \"NOT_DEFINED\", \"providerUrgency\": \"NOT_DEFINED\", \"version\": \"4.0\", \"baseSeverity\": \"HIGH\", \"baseScore\": 8.6, \"vectorString\": \"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N\"}}, {\"format\": \"CVSS\", \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}], \"cvssV3_1\": {\"attackVector\": \"LOCAL\", \"attackComplexity\": \"LOW\", \"privilegesRequired\": \"NONE\", \"userInteraction\": \"NONE\", \"scope\": \"UNCHANGED\", \"confidentialityImpact\": \"HIGH\", \"integrityImpact\": \"HIGH\", \"availabilityImpact\": \"HIGH\", \"version\": \"3.1\", \"baseSeverity\": \"HIGH\", \"baseScore\": 8.4, \"vectorString\": \"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\"}}], \"references\": [{\"url\": \"https://github.com/maquina-app/rails-mcp-server\", \"tags\": [\"product\"]}, {\"url\": \"https://github.com/maquina-app/rails-mcp-server/pull/59\", \"tags\": [\"issue-tracking\"]}, {\"url\": \"https://github.com/maquina-app/rails-mcp-server/releases\", \"tags\": [\"release-notes\"]}, {\"name\": \"VulnCheck Advisory: rails-mcp-server 1.4.0 through 1.6.0 OS Command Execution via execute_ruby PTY Escape\", \"tags\": [\"third-party-advisory\"], \"url\": \"https://www.vulncheck.com/advisories/rails-mcp-server-1.4.0-through-1.6.0-os-command-execution-via-execute-ruby-pty-escape\"}], \"credits\": [{\"lang\": \"en\", \"value\": \"Avishai Gonen (Pluto Security)\", \"type\": \"finder\"}], \"x_generator\": {\"engine\": \"vulncheck-endgame\"}, \"source\": {\"discovery\": \"UNKNOWN\"}}, \"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-81097\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-08-27T19:00:31.993065Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-08-27T19:00:40.771Z\"}}]}",
"cveMetadata": "{\"cveId\": \"CVE-2026-81097\", \"assignerOrgId\": \"83251b91-4cc7-4094-a5c7-464a1b83ea10\", \"state\": \"PUBLISHED\", \"assignerShortName\": \"VulnCheck\", \"dateReserved\": \"2026-08-26T16:00:32.686Z\", \"datePublished\": \"2026-08-27T14:50:37.617Z\", \"dateUpdated\": \"2026-08-28T15:59:55.991Z\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
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.
Loading…
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.
Loading…
Loading…