# CVE-2026-82685: Confirmation token accepted on any record in AshAuthentication

> An authenticated attacker can hijack another user's account by replaying their own email confirmation token against the victim's record.

- **Severity:** High 7.6 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** EEF-CVE-2026-82685, GHSA-g636-26vf-2w63

## What is CVE-2026-82685?

CVE-2026-82685 is a high-severity authentication bypass vulnerability in team-alembic ash_authentication, published on 17 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Authorization Bypass Through User-Controlled Key vulnerability in team-alembic AshAuthentication allows an authenticated attacker to overwrite and confirm another user's email address, and so take over that account. A confirmation token issued to one user is accepted on any other user's record.

AshAuthentication.AddOn.Confirmation.ConfirmChange verifies the token's signature and its act claim, then applies the changes stored against that token to whichever record the changeset targets, never comparing the sub claim against changeset.data. An attacker who registers an account and changes their own email replays the resulting token against a victim's record id, writing in their own address with force_change_attributes/2 and stamping confirmed_at, after which an ordinary password reset yields the account. The library's own confirmation flow is unaffected, because AshAuthentication.AddOn.Confirmation.Actions.confirm/3 resolves sub to a user and targets that record.

This issue affects ash_authentication: from 0.5.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-82685?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ash_authentication` | Hex | From 0.5.0 | 4.15.0, 5.0.0-rc.14 |

## How do I fix CVE-2026-82685?

Upgrade ash_authentication to a fixed version for your release line: 4.15.0 or 5.0.0-rc.14.

## Is CVE-2026-82685 being exploited?

There is no known exploitation of CVE-2026-82685 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82685 and fix it if it is affected.

What it is: CVE-2026-82685 is a high-severity authentication bypass vulnerability in team-alembic ash_authentication, published on 17 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-82685 in the wild and no public exploit code.

Affected packages and fixed versions:
- ash_authentication (Hex): affected from 0.5.0; fixed in 4.15.0, 5.0.0-rc.14

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-2026-82685/ (Markdown: https://insights.sbomify.com/CVE-2026-82685/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82685
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82685
- OSV: https://osv.dev/vulnerability/CVE-2026-82685

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82685/
Summaries are generated and may contain mistakes; the official description above is the record.