CVE-2026-17106
Tar extraction in moby/go-archive can write outside the destination directory via link following
- Published
- Aug 18, 2026
- Updated
- Aug 19, 2026
- Assigning CNA
- Docker
- Evidence observed
- Aug 28, 2026
Primary CVSS
nvd · CVSS 4.0
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XLow · next 30 days
- Percentile
- 25.7%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
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.
Sources
3PoC funcional de CVE-2026-17106 (CopyEscape): carrera TOCTOU en docker cp que permite escritura arbitraria en el host Docker. Laboratorio Docker + monitor inotify + LD_PRELOAD. Variante macOS inocua y Linux destructiva.
PoC repository for the blog post CopyEscape: Taking Over Docker Hosts with docker cp
Responsible use
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