# CVE-2026-121817: About Time Technologies｜Herowatch Go Server - Insecure Direct Object Reference


- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 4 Nov 2026
- **Updated:** 4 Nov 2026
- **Also known as:** GHSA-33f3-4jq2-r259

## What is CVE-2026-121817?

CVE-2026-121817 is a high-severity vulnerability in About Time Technologies Herowatch Go Server, published on 4 Nov 2026. 

### Official description

Herowatch Go Server developed by About Time Technologies has a Insecure Direct Object Reference vulnerability. Authenticated remote attackers can modify specific parameters to access or operate other users' data and functions.

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

## Which versions are affected by CVE-2026-121817?


## How do I fix CVE-2026-121817?

No fix has been published for CVE-2026-121817 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-121817 being exploited?

There is no known exploitation of CVE-2026-121817 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-121817 and fix it if it is affected.

What it is: CVE-2026-121817 is a high-severity vulnerability in About Time Technologies Herowatch Go Server, published on 4 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-121817 in the wild and no public exploit code.

Affected product: About Time Technologies Herowatch Go Server. 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-2026-121817/ (Markdown: https://insights.sbomify.com/CVE-2026-121817/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-121817
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-121817
- OSV: https://osv.dev/vulnerability/CVE-2026-121817

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-121817/
Summaries are generated and may contain mistakes; the official description above is the record.