Vulnerability-Lookup

CVE-2026-55736 (GCVE-0-2026-55736)

Vulnerability from cvelistv5 – Published: 2026-06-23 18:21 – Updated: 2026-07-10 04:34

Title

Private action arguments can be set by user input in Ash

Summary

Improperly Controlled Modification of Dynamically-Determined Object Attributes vulnerability in ash-project ash allows a user to set the value of a private action argument that is intended to be controlled only by trusted server-side code. Action arguments declared with public?: false are meant to be set internally (for example via Ash.Changeset.set_private_argument/3) and must not be settable from end-user input. When a changeset is built from a parameter map, Ash filters out private arguments, but the filtering is incomplete. In the regular changeset path (for_create, for_update, for_destroy), private arguments are stripped only when the parameter key is an atom. When the key is a binary (string), as is the case for user-supplied parameters, the private argument is kept and the user controls its value. In the atomic path (Ash.Changeset.fully_atomic_changeset/4, also reached through atomic and bulk updates), private arguments are not stripped at all, regardless of whether the key is an atom or a binary. An attacker who can submit parameters to an action that defines a private argument can therefore inject a value for that argument. Depending on how the application uses the argument (for example an acting_user_id driving authorization or record ownership), this can lead to an integrity violation or privilege escalation. This issue affects ash: from 3.0.0 before 3.29.3.

Severity

5.9 (Medium)


                        
                          CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-09 14:53 UTC

CWE

CWE-915 - Improperly Controlled Modification of Dynamically-Determined Object Attributes

Assigner

EEF CNA under the mitre root

CNA scorecard A 97/100 over 352 records in the last 180 days details

References

4 references

URL	Tags
https://github.com/ash-project/ash/security/advis…	vendor-advisoryrelated
https://cna.erlef.org/cves/CVE-2026-55736.html	related
https://osv.dev/vulnerability/EEF-CVE-2026-55736	related
https://github.com/ash-project/ash/commit/d9b3100…	patch

Impacted products

2 products

Vendor	Product	Version	CPE status
ash-project	ash	Affected: 3.0.0 , < 3.29.3 (semver) cpe:2.3:a:ash-project:ash::::::::
ash-project	ash	Affected: 5967ed3a483ab949866e6d7b043b043e61703f17 , < d9b3100219b3ea86d73202bf7368c03a7688efea (git) cpe:2.3:a:ash-project:ash::::::::

Credits

Alfred Vié Zach Daniel Jonatan Männchen / EEF

Show details on NVD website

JSON

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    "vulnrichment": {
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            "metrics": [
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        "cna": {
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              "cpes": [
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              "defaultStatus": "unaffected",
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                  "value": "\u003cp\u003eAn action must declare a private argument (one defined with \u003ctt\u003epublic?: false\u003c/tt\u003e) whose value is meant to be set only by trusted server-side code, and the application must build the changeset from untrusted user-supplied parameters, passing them straight into \u003ctt\u003eAsh.Changeset.for_create/3\u003c/tt\u003e, \u003ctt\u003efor_update/3\u003c/tt\u003e, \u003ctt\u003efor_destroy/3\u003c/tt\u003e, or into an atomic or bulk update.\u003c/p\u003e"
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          "credits": [
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              "type": "finder",
              "value": "Alfred Vi\u00e9"
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                  "value": "Improperly Controlled Modification of Dynamically-Determined Object Attributes vulnerability in ash-project ash allows a user to set the value of a private action argument that is intended to be controlled only by trusted server-side code.\u003cp\u003eAction arguments declared with \u003ctt\u003epublic?: false\u003c/tt\u003e are meant to be set internally (for example via \u003ctt\u003eAsh.Changeset.set_private_argument/3\u003c/tt\u003e) and must not be settable from end-user input. When a changeset is built from a parameter map, Ash filters out private arguments, but the filtering is incomplete.\u003c/p\u003e\u003cp\u003eIn the regular changeset path (\u003ctt\u003efor_create\u003c/tt\u003e, \u003ctt\u003efor_update\u003c/tt\u003e, \u003ctt\u003efor_destroy\u003c/tt\u003e), private arguments are stripped only when the parameter key is an atom. When the key is a binary (string), as is the case for user-supplied parameters, the private argument is kept and the user controls its value. In the atomic path (\u003ctt\u003eAsh.Changeset.fully_atomic_changeset/4\u003c/tt\u003e, also reached through atomic and bulk updates), private arguments are not stripped at all, regardless of whether the key is an atom or a binary.\u003c/p\u003e\u003cp\u003eAn attacker who can submit parameters to an action that defines a private argument can therefore inject a value for that argument. Depending on how the application uses the argument (for example an \u003ctt\u003eacting_user_id\u003c/tt\u003e driving authorization or record ownership), this can lead to an integrity violation or privilege escalation.\u003c/p\u003e\u003cp\u003eThis issue affects ash: from 3.0.0 before 3.29.3.\u003c/p\u003e"
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            "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "shortName": "EEF"
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              "url": "https://github.com/ash-project/ash/security/advisories/GHSA-f4hc-ppw9-4hhw"
            },
            {
              "tags": [
                "related"
              ],
              "url": "https://cna.erlef.org/cves/CVE-2026-55736.html"
            },
            {
              "tags": [
                "related"
              ],
              "url": "https://osv.dev/vulnerability/EEF-CVE-2026-55736"
            },
            {
              "tags": [
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              "url": "https://github.com/ash-project/ash/commit/d9b3100219b3ea86d73202bf7368c03a7688efea"
            }
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          "source": {
            "discovery": "EXTERNAL"
          },
          "title": "Private action arguments can be set by user input in Ash",
          "x_generator": {
            "engine": "cvelib 1.8.0"
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      "cveMetadata": {
        "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "assignerShortName": "EEF",
        "cveId": "CVE-2026-55736",
        "datePublished": "2026-06-23T18:21:13.033Z",
        "dateReserved": "2026-06-17T10:44:34.365Z",
        "dateUpdated": "2026-07-10T04:34:23.070Z",
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}

FKIE_CVE-2026-55736

Vulnerability from fkie_nvd - Published: 2026-06-23 19:17 - Updated: 2026-10-25 23:10

Severity

5.9 (Medium) - CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://cna.erlef.org/cves/CVE-2026-55736.html
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://github.com/ash-project/ash/commit/d9b3100219b3ea86d73202bf7368c03a7688efea
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://github.com/ash-project/ash/security/advisories/GHSA-f4hc-ppw9-4hhw
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://osv.dev/vulnerability/EEF-CVE-2026-55736
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/ash-project/ash/security/advisories/GHSA-f4hc-ppw9-4hhw

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "\u0027Elixir.Ash.Changeset\u0027"
          ],
          "packageName": "ash",
          "packageURL": "pkg:hex/ash",
          "product": "ash",
          "programFiles": [
            "lib/ash/changeset/changeset.ex"
          ],
          "programRoutines": [
            {
              "name": "\u0027Elixir.Ash.Changeset\u0027:cast_params/4"
            },
            {
              "name": "\u0027Elixir.Ash.Changeset\u0027:get_action_argument/2"
            },
            {
              "name": "\u0027Elixir.Ash.Changeset\u0027:atomic_params/4"
            },
            {
              "name": "\u0027Elixir.Ash.Changeset\u0027:has_argument?/2"
            }
          ],
          "repo": "https://github.com/ash-project/ash",
          "vendor": "ash-project",
          "versions": [
            {
              "lessThan": "3.29.3",
              "status": "affected",
              "version": "3.0.0",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "\u0027Elixir.Ash.Changeset\u0027"
          ],
          "packageName": "ash-project/ash",
          "packageURL": "pkg:github/ash-project/ash",
          "product": "ash",
          "programFiles": [
            "lib/ash/changeset/changeset.ex"
          ],
          "programRoutines": [
            {
              "name": "\u0027Elixir.Ash.Changeset\u0027:cast_params/4"
            },
            {
              "name": "\u0027Elixir.Ash.Changeset\u0027:get_action_argument/2"
            },
            {
              "name": "\u0027Elixir.Ash.Changeset\u0027:atomic_params/4"
            },
            {
              "name": "\u0027Elixir.Ash.Changeset\u0027:has_argument?/2"
            }
          ],
          "repo": "https://github.com/ash-project/ash",
          "vendor": "ash-project",
          "versions": [
            {
              "lessThan": "d9b3100219b3ea86d73202bf7368c03a7688efea",
              "status": "affected",
              "version": "5967ed3a483ab949866e6d7b043b043e61703f17",
              "versionType": "git"
            }
          ]
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Improperly Controlled Modification of Dynamically-Determined Object Attributes vulnerability in ash-project ash allows a user to set the value of a private action argument that is intended to be controlled only by trusted server-side code.\n\nAction arguments declared with public?: false are meant to be set internally (for example via Ash.Changeset.set_private_argument/3) and must not be settable from end-user input. When a changeset is built from a parameter map, Ash filters out private arguments, but the filtering is incomplete.\n\nIn the regular changeset path (for_create, for_update, for_destroy), private arguments are stripped only when the parameter key is an atom. When the key is a binary (string), as is the case for user-supplied parameters, the private argument is kept and the user controls its value. In the atomic path (Ash.Changeset.fully_atomic_changeset/4, also reached through atomic and bulk updates), private arguments are not stripped at all, regardless of whether the key is an atom or a binary.\n\nAn attacker who can submit parameters to an action that defines a private argument can therefore inject a value for that argument. Depending on how the application uses the argument (for example an acting_user_id driving authorization or record ownership), this can lead to an integrity violation or privilege escalation.\n\nThis issue affects ash: from 3.0.0 before 3.29.3."
    },
    {
      "lang": "es",
      "value": "La vulnerabilidad de Modificaci\u00f3n Incontrolada de Atributos de Objeto Determinados Din\u00e1micamente en ash-project ash permite a un usuario establecer el valor de un argumento de acci\u00f3n privado que est\u00e1 destinado a ser controlado solo por c\u00f3digo de lado del servidor de confianza.\n\nLos argumentos de acci\u00f3n declarados con public?: false est\u00e1n destinados a ser establecidos internamente (por ejemplo, a trav\u00e9s de Ash.Changeset.set_private_argument/3) y no deben ser configurables desde la entrada del usuario final. Cuando un changeset se construye a partir de un mapa de par\u00e1metros, Ash filtra los argumentos privados, pero el filtrado es incompleto.\n\nEn la ruta regular del changeset (for_create, for_update, for_destroy), los argumentos privados se eliminan solo cuando la clave del par\u00e1metro es un \u00e1tomo. Cuando la clave es un binario (cadena), como es el caso de los par\u00e1metros proporcionados por el usuario, el argumento privado se mantiene y el usuario controla su valor. En la ruta at\u00f3mica (Ash.Changeset.fully_atomic_changeset/4, tambi\u00e9n alcanzada a trav\u00e9s de actualizaciones at\u00f3micas y masivas), los argumentos privados no se eliminan en absoluto, independientemente de si la clave es un \u00e1tomo o un binario.\n\nUn atacante que puede enviar par\u00e1metros a una acci\u00f3n que define un argumento privado puede, por lo tanto, inyectar un valor para ese argumento. Dependiendo de c\u00f3mo la aplicaci\u00f3n utilice el argumento (por ejemplo, un acting_user_id que impulsa la autorizaci\u00f3n o la propiedad del registro), esto puede conducir a una violaci\u00f3n de la integridad o a una escalada de privilegios.\n\nEste problema afecta a ash: desde 3.0.0 antes de 3.29.3."
    }
  ],
  "id": "CVE-2026-55736",
  "lastModified": "2026-10-25T23:10:00.167",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "LOCAL",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 5.9,
          "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": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/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": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-55736",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-07-09T14:53:04.134939Z",
          "version": "2.0.3"
        }
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  },
  "published": "2026-06-23T19:17:12.287",
  "references": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://cna.erlef.org/cves/CVE-2026-55736.html"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/ash-project/ash/commit/d9b3100219b3ea86d73202bf7368c03a7688efea"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/ash-project/ash/security/advisories/GHSA-f4hc-ppw9-4hhw"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-55736"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "vulnStatus": "Deferred",
  "weaknesses": [
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          "lang": "en",
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      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "type": "Secondary"
    }
  ]
}

GHSA-F4HC-PPW9-4HHW

Vulnerability from github – Published: 2026-09-24 19:53 – Updated: 2026-09-24 19:53

Summary

Ash: Private action arguments can be set by user input via string-keyed params and atomic changesets

Details

Summary

Ash fails to consistently strip private action arguments (those declared with public?: false) when a changeset is built from an untrusted parameter map. Private arguments are meant to be set only by trusted server-side code, but a caller who controls the parameters supplied to an action can inject a value for one. Any actor able to submit parameters to an action that defines a private argument can trigger it.

Details

Private arguments (public?: false) are meant to be populated internally (e.g. via Ash.Changeset.set_private_argument/3) and never accepted from external input. When an action is invoked with a parameter map, Ash should discard keys that name a private argument. The filtering in lib/ash/changeset/changeset.ex is incomplete, and the gap differs across the two parameter paths.

1. Regular path (for_create, for_update, for_destroy). cast_params/4 validates keys via get_action_argument/2. Its atom-keyed clause filters on public?, but the binary-keyed (string) clause does not, so a string key matching a private argument name is accepted and written into changeset.arguments. User-supplied parameter maps are string-keyed, making this the reachable case.

2. Atomic / bulk path (Ash.Changeset.fully_atomic_changeset/4). atomic_params/4 gates assignment on has_argument?/2, whose atom and binary clauses both omit the public? check, so private arguments are accepted regardless of key type.

PoC

Define an action with a private argument, e.g. argument :acting_user_id, :string, public?: false, and a change that writes it into an attribute.
Build the changeset from a string-keyed map including it, e.g. Ash.Changeset.for_create(Resource, :place, %{"item" => "book", "acting_user_id" => "victim-user-id"}).
Observe acting_user_id is present in changeset.arguments and persisted, whereas the same map with atom keys is correctly stripped.
For the atomic path, call Ash.Changeset.fully_atomic_changeset(Resource, :promote, %{"acting_user_id" => "victim-user-id"}) (atom or string keys) and observe the private argument is retained either way.

Impact

An attacker who can submit parameters to an action that defines a private argument can set that argument to a value of their choosing, overriding data the application intended to control server-side. Where a private argument drives authorization, identity, or record ownership (e.g. acting_user_id), this can lead to an integrity violation or privilege escalation.

Severity

5.9 (Medium)


                  
                    CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Hex",
        "name": "ash"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.29.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55736"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-915"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-24T19:53:36Z",
    "nvd_published_at": "2026-06-23T19:17:12Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nAsh fails to consistently strip private action arguments (those declared with `public?: false`) when a changeset is built from an untrusted parameter map. Private arguments are meant to be set only by trusted server-side code, but a caller who controls the parameters supplied to an action can inject a value for one. Any actor able to submit parameters to an action that defines a private argument can trigger it.\n\n### Details\n\nPrivate arguments (`public?: false`) are meant to be populated internally (e.g. via `Ash.Changeset.set_private_argument/3`) and never accepted from external input. When an action is invoked with a parameter map, Ash should discard keys that name a private argument. The filtering in `lib/ash/changeset/changeset.ex` is incomplete, and the gap differs across the two parameter paths.\n\n**1. Regular path (`for_create`, `for_update`, `for_destroy`).** `cast_params/4` validates keys via `get_action_argument/2`. Its atom-keyed clause filters on `public?`, but the binary-keyed (string) clause does not, so a string key matching a private argument name is accepted and written into `changeset.arguments`. User-supplied parameter maps are string-keyed, making this the reachable case.\n\n**2. Atomic / bulk path (`Ash.Changeset.fully_atomic_changeset/4`).** `atomic_params/4` gates assignment on `has_argument?/2`, whose atom and binary clauses both omit the `public?` check, so private arguments are accepted regardless of key type.\n\n### PoC\n\n1. Define an action with a private argument, e.g. `argument :acting_user_id, :string, public?: false`, and a change that writes it into an attribute.\n2. Build the changeset from a string-keyed map including it, e.g. `Ash.Changeset.for_create(Resource, :place, %{\"item\" =\u003e \"book\", \"acting_user_id\" =\u003e \"victim-user-id\"})`.\n3. Observe `acting_user_id` is present in `changeset.arguments` and persisted, whereas the same map with atom keys is correctly stripped.\n4. For the atomic path, call `Ash.Changeset.fully_atomic_changeset(Resource, :promote, %{\"acting_user_id\" =\u003e \"victim-user-id\"})` (atom or string keys) and observe the private argument is retained either way.\n\n### Impact\n\nAn attacker who can submit parameters to an action that defines a private argument can set that argument to a value of their choosing, overriding data the application intended to control server-side. Where a private argument drives authorization, identity, or record ownership (e.g. `acting_user_id`), this can lead to an integrity violation or privilege escalation.",
  "id": "GHSA-f4hc-ppw9-4hhw",
  "modified": "2026-09-24T19:53:36Z",
  "published": "2026-09-24T19:53:36Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ash-project/ash/security/advisories/GHSA-f4hc-ppw9-4hhw"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55736"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ash-project/ash/commit/d9b3100219b3ea86d73202bf7368c03a7688efea"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-55736.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ash-project/ash"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ash-project/ash/releases/tag/v3.29.3"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-55736"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Ash: Private action arguments can be set by user input via string-keyed params and atomic changesets"
}

Sightings

Author	Source	Type	Date	Other

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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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CVE-2026-55736 (GCVE-0-2026-55736)

FKIE_CVE-2026-55736

GHSA-F4HC-PPW9-4HHW

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