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

Vulnerability from cvelistv5 – Published: 2026-06-23 18:21 – Updated: 2026-06-23 18:21
VLAI
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
CWE
  • CWE-915 - Improperly Controlled Modification of Dynamically-Determined Object Attributes
Assigner
EEF
References
Impacted products
Vendor Product Version
ash-project ash Affected: 3.0.0 , < 3.29.3 (semver)
    cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*
 Create a notification for this product.
ash-project ash Affected: 5967ed3a483ab949866e6d7b043b043e61703f17 , < d9b3100219b3ea86d73202bf7368c03a7688efea (git)
    cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*
 Create a notification for this product.
Credits
Alfred Vié Zach Daniel Jonatan Männchen / EEF
Show details on NVD website
To clipboard 

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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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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.

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  • 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.
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Detection rules are retrieved from Rulezet.