# CVE-2026-61672: Capsule: Tenant owner bypasses Capsule's forbidden namespace/service/node label and annotation enforcement

> Tenant owners can bypass Capsule's forbidden label and annotation enforcement due to a sorting bug, allowing them to violate cluster policies and tenant boundaries.

- **Severity:** High 7.1 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:H/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:** 18 Sep 2026
- **Updated:** 22 Sep 2026
- **Also known as:** GHSA-gjw4-3v3v-rqxg, GO-2026-6520

## What is CVE-2026-61672?

CVE-2026-61672 is a high-severity vulnerability in projectcapsule capsule, published on 18 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Capsule is a multi-tenancy and policy-based framework for Kubernetes. Prior to 0.13.7, ForbiddenListSpec.ExactMatch in pkg/api/forbidden_list.go sorts denied metadata keys case-insensitively and then uses sort.SearchStrings, which assumes byte-order sorting. When an administrator's forbidden list mixes capitalized and lowercase keys or otherwise has different case-insensitive and byte ordering, the binary search can return false for a key that is present. An authenticated tenant owner can then pass the missed key through api.ValidateForbidden and bypass configured namespace, Service, or delegated node metadata restrictions, potentially influencing cluster policies, network exposure, or scheduling outside the tenant boundary. Uniformly lowercase lists whose two orderings coincide are not affected. This issue is fixed in version 0.13.7.

Weakness: CWE-863 (Incorrect Authorization), CWE-697 (Incorrect Comparison)

## Which versions are affected by CVE-2026-61672?

3 open source packages ship an affected version, including github.com/projectcapsule/capsule.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/projectcapsule/capsule` | Go | All versions | 0.13.7 |
| `github.com/projectcapsule/capsule` | Go | All versions | 0.13.7 |
| `github.com/projectcapsule/capsule` | Go | All versions | 0.13.7 |

## How do I fix CVE-2026-61672?

Upgrade github.com/projectcapsule/capsule to 0.13.7 or later.

## Is CVE-2026-61672 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-61672 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-61672 and fix it if it is affected.

What it is: CVE-2026-61672 is a high-severity vulnerability in projectcapsule capsule, published on 18 Sep 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-2026-61672 exists.

Affected packages and fixed versions:
- github.com/projectcapsule/capsule (Go): affected all versions; fixed in 0.13.7
- github.com/projectcapsule/capsule (Go): affected all versions; fixed in 0.13.7
- github.com/projectcapsule/capsule (Go): affected all versions; fixed in 0.13.7

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-2026-61672/ (Markdown: https://insights.sbomify.com/CVE-2026-61672/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-61672
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-61672
- OSV: https://osv.dev/vulnerability/CVE-2026-61672

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-61672/
Summaries are generated and may contain mistakes; the official description above is the record.