---
title: "CVE-2023-48312: Capsule Proxy Authentication bypass using an empty token"
url: https://erroneo.us/security/cve/CVE-2023-48312/
description: "CVE-2023-48312 (github.com/projectcapsule/capsule-proxy (Go)): capsule-proxy is a reverse proxy for the capsule operator project. Affected versions are…"
type: vulnerability-record
section: "Security Digest"
date_published: 2023-11-24
date_modified: 2024-08-02
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2023-48312"
kev: false
cvss: 9.8
epss: 0.00574
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2023-48312: Capsule Proxy Authentication bypass using an empty token

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.6% , percentile 47: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 47% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes github.com/projectcapsule/capsule-proxy (Go) <= 0.4.5, fixed in 0.4.6 ; github.com/clastix/capsule-proxy (Go) <= 0.4.5, fixed in 0.4.6 . Check your lockfile, including transitive dependencies.

## What it is

capsule-proxy is a reverse proxy for the capsule operator project. Affected versions are subject to a privilege escalation vulnerability which is based on a missing check if the user is authenticated based on the TokenReview result. All the clusters running with the anonymous-auth Kubernetes API Server setting disable (set to false) are affected since it would be possible to bypass the token review mechanism, interacting with the upper Kubernetes API Server. This privilege escalation cannot be exploited if you're relying only on client certificates (SSL/TLS). This vulnerability has been addressed in version 0.4.6. Users are advised to upgrade.

## Affected packages

- Go `github.com/projectcapsule/capsule-proxy` <= 0.4.5 → fixed: 0.4.6
- Go `github.com/clastix/capsule-proxy` <= 0.4.5 → fixed: 0.4.6

## Affected products (CVE record)

- projectcapsule capsule-proxy: < 0.4.6

## Severity

- GitHub_M CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- FIRST EPSS (model of 2026-10-21): 0.57% probability of exploitation activity in the next 30 days; percentile 47.

## Sources

- [GitHub Advisory GHSA-fpvw-6m5v-hqfp](https://github.com/advisories/GHSA-fpvw-6m5v-hqfp)
- [CVE.org record CVE-2023-48312](https://www.cve.org/CVERecord?id=CVE-2023-48312)
- [NVD entry CVE-2023-48312](https://nvd.nist.gov/vuln/detail/CVE-2023-48312)
- [github.com](https://github.com/projectcapsule/capsule-proxy/security/advisories/GHSA-fpvw-6m5v-hqfp)
- [github.com](https://github.com/projectcapsule/capsule-proxy/commit/472404f7006a4152e4eec76dee07324dd1e6e823)

---
Source page: https://erroneo.us/security/cve/CVE-2023-48312/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt