# CVE-2026-55222: Isar: Unprivileged user ownership of trusted repository GPG public keys storage after bootstrap


- **Severity:** Medium 5.1 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 23 Oct 2026
- **Updated:** 23 Oct 2026
- **Also known as:** GHSA-rq66-pfw5-whqq

## What is CVE-2026-55222?

CVE-2026-55222 is a medium-severity vulnerability in ilbers isar, published on 23 Oct 2026. 

### Official description

Isar is an integration system for automated root filesystem generation. In versions 0.11 and newer, /etc/apt/trusted.gpg.d is created manually during bootstrap setup to be able to deploy local keys. By that, the directory is owned by the calling user (the one that executes Isar) instead of root. If the calling user's id is identical to one of an unprivileged user inside the image, this user is able to alter existing keys and deploy new ones, silently breaking the apt repo integrity protection. The issue is has no impact on those images that use an immutable rootfs, or if apt is never invoked. Changing only the keys does not trigger an exploit, it's just one step in a chain. An attacker would also have to manipulate a remote repo or intercept non-secure communication with it. This issue has been patched via commit 29e84ed.

Weakness: CWE-1290 (Incorrect Decoding of Security Identifiers)

## Which versions are affected by CVE-2026-55222?


## How do I fix CVE-2026-55222?

No fix has been published for CVE-2026-55222 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-55222 being exploited?

There is no known exploitation of CVE-2026-55222 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55222 and fix it if it is affected.

What it is: CVE-2026-55222 is a medium-severity vulnerability in ilbers isar, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-55222 in the wild and no public exploit code.

Affected product: ilbers isar. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-55222/ (Markdown: https://insights.sbomify.com/CVE-2026-55222/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55222
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55222
- OSV: https://osv.dev/vulnerability/CVE-2026-55222

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55222/
Summaries are generated and may contain mistakes; the official description above is the record.