# CVE-2026-53521: Nezha Monitoring: Stored future DDNS profile ID allows unauthorized use of another user's DDNS profile context

> Attackers can persist invalid DDNS profile IDs to hijack another user's DDNS configuration context when that profile is later created.

- **Severity:** Medium 6.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:L`)
- **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:** 12 Jun 2026
- **Updated:** 15 Jun 2026
- **Also known as:** GHSA-39g2-8x68-pmx8, GO-2026-5826

## What is CVE-2026-53521?

CVE-2026-53521 is a medium-severity missing authorization vulnerability in nezhahq nezha, published on 12 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Nezha Monitoring is a self-hostable, lightweight, servers and websites monitoring and O&M tool. From version 2.0.14 to before version 2.1.0, PATCH /server/{id} accepts and persists nonexistent ddns_profiles IDs for a member-owned server. If another user later creates a DDNS profile with one of those IDs, the DDNS worker resolves the stored ID and dispatches an update using the other user's DDNS profile configuration in the context of the attacker's server. This issue has been patched in version 2.1.0.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-53521?

3 open source packages ship an affected version, including github.com/nezhahq/nezha.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/nezhahq/nezha` | Go | All versions | None |
| `github.com/nezhahq/nezha` | Go | From 2.0.14 | 2.1.0 |
| `github.com/nezhahq/nezha` | Go | From 2.0.14 | 2.1.0 |

## How do I fix CVE-2026-53521?

Upgrade github.com/nezhahq/nezha to 2.1.0 or later.

## Is CVE-2026-53521 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53521 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53521 and fix it if it is affected.

What it is: CVE-2026-53521 is a medium-severity missing authorization vulnerability in nezhahq nezha, published on 12 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53521 exists.

Affected packages and fixed versions:
- github.com/nezhahq/nezha (Go): affected all versions; no fix listed
- github.com/nezhahq/nezha (Go): affected from 2.0.14; fixed in 2.1.0
- github.com/nezhahq/nezha (Go): affected from 2.0.14; fixed in 2.1.0

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-2026-53521/ (Markdown: https://insights.sbomify.com/CVE-2026-53521/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53521
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53521
- OSV: https://osv.dev/vulnerability/CVE-2026-53521

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53521/
Summaries are generated and may contain mistakes; the official description above is the record.