# CVE-2026-84321: Nginx UI: Standalone short tokens survive administrative revocation in cache and authenticate again after account re-enable

> Attackers can reuse revoked short tokens to regain access to Nginx UI routes if the associated account is re-enabled, bypassing authentication controls.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N`)
- **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 Oct 2026
- **Updated:** 13 Oct 2026
- **Also known as:** GHSA-wq4w-vwvq-q3x9, GO-2026-6801

## What is CVE-2026-84321?

CVE-2026-84321 is a medium-severity authentication bypass vulnerability in 0xJacky nginx-ui, published on 12 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Nginx UI is a web user interface for the Nginx web server. Prior to 2.4.1, GenerateShortToken creates standalone short-token records without a long Token value, but DeleteUserTokens invalidates cached entries only when the long Token field is nonempty. A revoked short token can therefore remain in the short_token cache and authenticate again if the associated account is re-enabled before the cache entry expires because GetTokenUserByShortToken reads the surviving entry, restoring access to HTTP or WebSocket routes that accept short-token authentication. This issue is fixed in version 2.4.1.

Weakness: CWE-613 (DEPRECATED: Insufficient Session Expiration)

## Which versions are affected by CVE-2026-84321?

3 open source packages ship an affected version, including github.com/0xJacky/Nginx-UI.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/0xJacky/Nginx-UI` | Go | All versions | 1.9.10-0.20260703131214-23d1934099b0 |
| `github.com/0xJacky/Nginx-UI` | Go | All versions | 1.9.10-0.20260703131214-23d1934099b0 |
| `github.com/0xJacky/Nginx-UI` | Go | All versions | 1.9.10-0.20260703131214-23d1934099b0 |

## How do I fix CVE-2026-84321?

Upgrade github.com/0xJacky/Nginx-UI to 1.9.10-0.20260703131214-23d1934099b0 or later.

## Is CVE-2026-84321 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-84321 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-84321 and fix it if it is affected.

What it is: CVE-2026-84321 is a medium-severity authentication bypass vulnerability in 0xJacky nginx-ui, published on 12 Oct 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-2026-84321 exists.

Affected packages and fixed versions:
- github.com/0xJacky/Nginx-UI (Go): affected all versions; fixed in 1.9.10-0.20260703131214-23d1934099b0
- github.com/0xJacky/Nginx-UI (Go): affected all versions; fixed in 1.9.10-0.20260703131214-23d1934099b0
- github.com/0xJacky/Nginx-UI (Go): affected all versions; fixed in 1.9.10-0.20260703131214-23d1934099b0

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-2026-84321/ (Markdown: https://insights.sbomify.com/CVE-2026-84321/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-84321
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-84321
- OSV: https://osv.dev/vulnerability/CVE-2026-84321

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-84321/
Summaries are generated and may contain mistakes; the official description above is the record.