# CVE-2026-101090: Nezha through 2.2.3 Host Header Injection via OAuth2 redirect_uri

> Attackers can hijack OAuth2 login flows by injecting a malicious Host header, leading to account takeover when the dashboard_host setting is empty.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Sep 2026
- **Updated:** 28 Sep 2026
- **Also known as:** GHSA-62gj-x2f3-j2wj, GHSA-rf68-8gjr-36q7, GO-2026-6486

## What is CVE-2026-101090?

CVE-2026-101090 is a critical vulnerability in nezhahq nezha, published on 27 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Nezha 2.2.3 contains a Host header injection regression in the OAuth2 redirect endpoint. When the new optional dashboard_host setting is empty, /api/v1/oauth2/{provider} (cmd/dashboard/controller/oauth2.go) reflects the attacker-supplied HTTP Host header into the redirect_uri sent to the identity provider instead of falling back to the configured install_host. An attacker who induces a victim to begin OAuth2 login via a request that reaches Nezha with a forged Host header can cause an attacker-controlled callback URL to be used as the redirect_uri; if the OAuth2 provider accepts it, the victim's authorization code is delivered to the attacker origin, allowing the attacker to complete the OAuth2 login/binding flow and take over the account. This regresses the fix for GHSA-9rc6-8cjv-rcvx and is configuration-dependent (dashboard_host empty). At the time of the advisory no patched version was available.

Weakness: CWE-601 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2026-101090?

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 | All versions | None |
| `github.com/nezhahq/nezha` | Go | All versions | None |

## How do I fix CVE-2026-101090?

No fix has been published for CVE-2026-101090 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-101090 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-101090 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-101090 and fix it if it is affected.

What it is: CVE-2026-101090 is a critical vulnerability in nezhahq nezha, published on 27 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-101090 exists.

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

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-2026-101090/ (Markdown: https://insights.sbomify.com/CVE-2026-101090/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-101090
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-101090
- OSV: https://osv.dev/vulnerability/CVE-2026-101090

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-101090/
Summaries are generated and may contain mistakes; the official description above is the record.