# CVE-2026-55828: qbee transport: Symlink-chain path traversal in tar extraction (one level outside destination)

> Attackers can exploit symlink chains in tar extraction to write files outside the destination, potentially gaining root privileges in qbee-agent.

- **Severity:** Medium 6.0 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA: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:** 15 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** GHSA-f9m7-vc86-p6jj, GO-2026-5352

## What is CVE-2026-55828?

CVE-2026-55828 is a medium-severity path traversal vulnerability in qbee-io transport, published on 15 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

qbee transport is a remote access transport protocol implementation. Prior to 1.26.25, the extractTar routine uses strictly lexical path validation that does not account for on-disk symlinks created earlier in the extraction process. A crafted tar archive can use a symlink chain to write or overwrite files one directory level above the intended extraction path. When qbee-agent performs the extraction with root privileges, this permits a root-privileged file write outside the intended destination. This issue is fixed in version 1.26.25.

Weakness: CWE-59 (Improper Link Resolution Before File Access), CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-55828?

3 open source packages ship an affected version, including go.qbee.io/transport.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `go.qbee.io/transport` | Go | All versions | 1.26.25 |
| `go.qbee.io/transport` | Go | All versions | 1.26.25 |
| `go.qbee.io/transport` | Go | All versions | 1.26.25 |

## How do I fix CVE-2026-55828?

Upgrade go.qbee.io/transport to 1.26.25 or later.

## Is CVE-2026-55828 being exploited?

There is no known exploitation of CVE-2026-55828 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55828 and fix it if it is affected.

What it is: CVE-2026-55828 is a medium-severity path traversal vulnerability in qbee-io transport, published on 15 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-55828 in the wild and no public exploit code.

Affected packages and fixed versions:
- go.qbee.io/transport (Go): affected all versions; fixed in 1.26.25
- go.qbee.io/transport (Go): affected all versions; fixed in 1.26.25
- go.qbee.io/transport (Go): affected all versions; fixed in 1.26.25

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-2026-55828/ (Markdown: https://insights.sbomify.com/CVE-2026-55828/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55828
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55828
- OSV: https://osv.dev/vulnerability/CVE-2026-55828

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55828/
Summaries are generated and may contain mistakes; the official description above is the record.