# CVE-2026-93477: Private action arguments can be set by user input on the bulk destroy and bulk update paths in Ash

> Attackers can set private action arguments in bulk operations, potentially leading to privilege escalation or data integrity violations.

- **Severity:** Medium 5.9 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Sep 2026
- **Updated:** 25 Sep 2026
- **Also known as:** EEF-CVE-2026-93477, GHSA-c2p4-p7q6-hr2j

## What is CVE-2026-93477?

CVE-2026-93477 is a medium-severity missing authorization vulnerability in ash-project ash, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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 on the bulk destroy and bulk update paths.

Action arguments declared with public?: false are meant to be set only by trusted server-side code (for example via Ash.Changeset.set_private_argument/3) and must not be settable from end-user input. CVE-2026-55736 fixed the non-bulk changeset path to strip private arguments from user-supplied parameter maps, but the bulk destroy and bulk update paths were not covered.

Ash.Actions.Destroy.Bulk.base_changeset/5 and Ash.Actions.Update.Bulk.base_changeset/5 match every key in the caller-supplied parameter map against all of the action's arguments with no public? check, then apply the matches to the base changeset. A caller who can submit parameters to a bulk destroy or bulk update action (for example through AshJsonApi, AshGraphql, or a controller that forwards request parameters to Ash.bulk_destroy/4 or Ash.bulk_update/4) can therefore set any private argument of that action, including one referenced by an arg(...) template in the action's changes or validations. Depending on how the application uses the argument (for example an acting_user_id driving authorization or record ownership, or audit metadata), this can lead to an integrity violation or privilege escalation.

The fix requires public? in the argument matching on both bulk paths; private arguments remain settable server-side via the :private_arguments option.

This issue affects ash: from 2.17.15 before 3.33.11.

Weakness: CWE-915 (Improperly Controlled Modification of Dynamically-Determined Object Attributes)

## Which versions are affected by CVE-2026-93477?

1 open source package ship an affected version, including ash.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ash` | Hex | From 2.17.15 | 3.33.11 |

## How do I fix CVE-2026-93477?

Upgrade ash to 3.33.11 or later.

## Is CVE-2026-93477 being exploited?

There is no known exploitation of CVE-2026-93477 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93477 and fix it if it is affected.

What it is: CVE-2026-93477 is a medium-severity missing authorization vulnerability in ash-project ash, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-93477 in the wild and no public exploit code.

Affected packages and fixed versions:
- ash (Hex): affected from 2.17.15; fixed in 3.33.11

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-93477/ (Markdown: https://insights.sbomify.com/CVE-2026-93477/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93477
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93477
- OSV: https://osv.dev/vulnerability/CVE-2026-93477

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93477/
Summaries are generated and may contain mistakes; the official description above is the record.