Path Traversal in Containerd
CVE-2021-41103
containerd is an open source container runtime with an emphasis on simplicity, robustness and portability. A bug was found in containerd where container root directories and some plugins had insufficiently restricted permissions, allowing otherwise unprivileged Linux users to traverse directory contents and execute programs. When containers included executable programs with extended permission bits (such as setuid), unprivileged Linux users could discover and execute those programs. When the UID of an unprivileged Linux user on the host collided with the file owner or group inside a container, the unprivileged Linux user on the host could discover, read, and modify those files. This vulnerability has been fixed in containerd 1.4.11 and containerd 1.5.7. Users should update to these version when they are released and may restart containers or update directory permissions to mitigate the vulnerability. Users unable to update should limit access to the host to trusted users. Update directory permission on container bundles directories.
Vulnerability class: Path Traversal (Directory Traversal)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (41.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 42nd percentile — 41.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Containerd — versions < 1.4.11, >= 1.5.0, < 1.5.7
- Linuxfoundation Containerd
- Debian Linux — versions 11.0
- Fedoraproject Fedora — versions 34, 35
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/containerd/containerd/security/advisories/GHSA-c2h3-6mxw-7mvq (Third Party Advisory)
- github.com/containerd/containerd/commit/5b46e404f6b9f661a205e28d59c982d3634148f8 (Patch, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- www.debian.org/security/2021/dsa-5002 (vendor-advisory, Third Party Advisory)
- cert-portal.siemens.com/productcert/pdf/ssa-222547.pdf
- security.gentoo.org/glsa/202401-31 (vendor-advisory)
Frequently asked questions
- What is CVE-2021-41103?
- CVE-2021-41103 is a high-severity vulnerability in Containerd, classified under Path Traversal. CVSS score: 7.8/10. Published 2021-10-04.
- How severe is CVE-2021-41103?
- High severity. CVSS v3 base score is 7.8 out of 10.
- Is CVE-2021-41103 known to be exploited?
- 4 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.