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.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
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
Which versions are affected by CVE-2026-53521?
3 open source packages ship an affected version, including github.com/nezhahq/nezha.
| Package | 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.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-53521 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53521 exists.
Sources
Also known as GHSA-39g2-8x68-pmx8, GO-2026-5826.