# CVE-2026-48976: HomeBox: Cross-Tenant IDOR in Notifier Update Leaks Shoutrrr Credentials and Allows Webhook Hijack

> Authenticated users can access or modify other tenants' notifiers, leaking credentials and hijacking webhooks in HomeBox.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Sep 2026
- **Updated:** 21 Sep 2026
- **Also known as:** GHSA-mc8h-5c5v-37p7

## What is CVE-2026-48976?

CVE-2026-48976 is a high-severity missing authorization vulnerability in sysadminsmedia homebox, published on 21 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

HomeBox is a home inventory and organization system. Prior to 0.26.0, NotifierRepository.Update in backend/internal/data/repo/repo_notifier.go updates a notifier through UpdateOneID(id) without requiring the record's user ID to match the authenticated user. An authenticated user who supplies another tenant's notifier UUID to PUT /v1/notifiers/{id} can read the returned stored url, which may contain plaintext Shoutrrr credentials for Slack, SMTP, Telegram, Pushover, or Discord, and can replace the URL to redirect the victim's notifications to an attacker-controlled webhook. This issue is fixed in version 0.26.0.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key), CWE-522 (Insufficiently Protected Credentials)

## Which versions are affected by CVE-2026-48976?


## How do I fix CVE-2026-48976?

No fix has been published for CVE-2026-48976 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-48976 being exploited?

There is no known exploitation of CVE-2026-48976 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-48976 and fix it if it is affected.

What it is: CVE-2026-48976 is a high-severity missing authorization vulnerability in sysadminsmedia homebox, published on 21 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-2026-48976 in the wild and no public exploit code.

Affected product: sysadminsmedia homebox. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-48976/ (Markdown: https://insights.sbomify.com/CVE-2026-48976/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48976
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48976
- OSV: https://osv.dev/vulnerability/CVE-2026-48976

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-48976/
Summaries are generated and may contain mistakes; the official description above is the record.