Path Traversal in Docker
CVE-2021-21284
In Docker before versions 9.03.15, 20.10.3 there is a vulnerability involving the --userns-remap option in which access to remapped root allows privilege escalation to real root. When using "--userns-remap", if the root user in the remapped namespace has access to the host filesystem they can modify files under "/var/lib/docker/<remapping>" that cause writing files with extended privileges. Versions 20.10.3 and 19.03.15 contain patches that prevent privilege escalation from remapped user.
Vulnerability class: Path Traversal (Directory Traversal)
EPSS: 0.011 (61.2th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N.
Affected products
- Docker
- Moby — versions < 19.03.15, >= 20.0.0, < 20.10.3
- Netapp E-series_santricity_os_controller
- Debian Debian_linux — versions 10.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (x_refsource_MISC, Release Notes, Vendor Advisory)
- security-advisories@github.com (Third Party Advisory, x_refsource_MISC, Release Notes)
- security-advisories@github.com (Third Party Advisory, x_refsource_MISC, Release Notes)
- security-advisories@github.com (x_refsource_CONFIRM, Third Party Advisory)
- security-advisories@github.com (Patch, Third Party Advisory, x_refsource_MISC)
- security-advisories@github.com (x_refsource_CONFIRM, Third Party Advisory)
- security-advisories@github.com (vendor-advisory, Third Party Advisory, x_refsource_DEBIAN)
- security-advisories@github.com (vendor-advisory, Patch, Third Party Advisory, x_refsource_GENTOO)
Frequently asked questions
- What is CVE-2021-21284?
- CVE-2021-21284 is a medium-severity vulnerability in Docker, classified under Path Traversal. CVSS score: 6.8/10. Published 2021-02-02.
- How severe is CVE-2021-21284?
- Medium severity. CVSS v3 base score is 6.8 out of 10.
- Is CVE-2021-21284 known to be exploited?
- 6 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.