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Public proof of conceptFix available

CVE-2020-15257

A public proof of concept exists; no exploitation attested.

  • Published2020-12-01
  • Fixed in1.4.3 · 1.3.9
  • WeaknessCWE-669

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

containerd is an industry-standard container runtime and is available as a daemon for Linux and Windows. In containerd before versions 1.3.9 and 1.4.3, the containerd-shim API is improperly exposed to host network containers. Access controls for the shim’s API socket verified that the connecting process had an effective UID of 0, but did not otherwise restrict access to the abstract Unix domain socket. This would allow malicious containers running in the same network namespace as the shim, with an effective UID of 0 but otherwise reduced privileges, to cause new processes to be run with elevated privileges. This vulnerability has been fixed in containerd 1.3.9 and 1.4.3. Users should update to these versions as soon as they are released. It should be noted that containers started with an old version of containerd-shim should be stopped and restarted, as running containers will continue to be vulnerable even after an upgrade. If you are not providing the ability for untrusted users to start containers in the same network namespace as the shim (typically the "host" network namespace, for example with docker run --net=host or hostNetwork: true in a Kubernetes pod) and run with an effective UID of 0, you are not vulnerable to this issue. If you are running containers with a vulnerable configuration, you can deny access to all abstract sockets with AppArmor by adding a line similar to deny unix addr=@**, to your policy. It is best practice to run containers with a reduced set of privileges, with a non-zero UID, and with isolated namespaces. The containerd maintainers strongly advise against sharing namespaces with the host. Reducing the set of isolation mechanisms used for a container necessarily increases that container's privilege, regardless of what container runtime is used for running that container.

Timeline

dates in UTC
  1. 2020-12-0103:15CVE publishedNVD
  2. 2026-10-2319:23First public proof of conceptPoC-in-GitHub

Versions per branch

NVD · OSV
Linuxfoundation containerd
BranchAffectedFixed in
1.4≥ 1.4.0, < 1.4.31.4.3
1.3< 1.3.91.3.9
Debian debian linux
BranchAffectedFixed in
10.0= 10.0no fix published
Fedoraproject fedora
BranchAffectedFixed in
33.x= 33no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • containerdUbuntu:20.04:LTSall versions · fixed in 1.3.3-0ubuntu2.2
  • containerdUbuntu:20.04:LTSall versions · fixed in 1.3.3-0ubuntu2.1
  • containerdUbuntu:18.04:LTSall versions · fixed in 1.3.3-0ubuntu1~18.04.4
  • containerdUbuntu:18.04:LTSall versions · fixed in 1.3.3-0ubuntu1~18.04.3
  • containerdUbuntu:16.04:LTSall versions · fixed in 1.2.6-0ubuntu1~16.04.6
  • containerdUbuntu:16.04:LTSall versions · fixed in 1.2.6-0ubuntu1~16.04.5
  • containerdSUSE:Manager Server 4.0all versions · fixed in 1.3.9-5.29.3
  • containerdSUSE:Manager Retail Branch Server 4.0all versions · fixed in 1.3.9-5.29.3

118 more package ranges on OSV.dev

Vendor advisories

  • RHSA-2022:2183 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Release of containers for OSP 16.2.z director operator tech preview

Full record on NVD

Fix

  1. Update Linuxfoundation containerd to 1.4.3 · 1.3.9
  2. Vendor fix Red Hat Product Security RHSA-2022:2183 · 1 productOSP 16.2 Release - OSP Director Operator Containers tech preview

Advisories and patches

Detection

read 2026-11-01 01:02 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • CNACVSS 3.15.2known since 2026-10-23
  • NVDCVSS 3.15.2read 2026-10-23
  • NVDCVSS 2.03.6read 2026-10-23
  • CNAweakness (CWE)CWE-669known since 2026-10-23
  • NVDweakness (CWE)CWE-669read 2026-10-23
  • FIRST EPSSEPSS score3.1 %2026-11-08
  • PoC-in-GitHubproof of concept1known since 2026-11-01
  • OSVaffected packages—
  • GitHub AdvisoriesadvisoryMODERATE2021-05-21

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
Published
2020-12-01
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-36xw-fx78-c5r4

Frequently asked questions

What is CVE-2020-15257?

containerd is an industry-standard container runtime and is available as a daemon for Linux and Windows. In containerd before versions 1.3.9 and 1.4.3, the containerd-shim API is improperly exposed to host network containers. Access controls for the shim’s API socket verified that the connecting process had an effective UID of 0, but did not otherwise restrict access to the abstract Unix domain socket. This would allow malicious containers running in the same network namespace as the shim, with an effective UID of 0 but otherwise reduced privileges, to cause new processes to be run with elevated privileges. This vulnerability has been fixed in containerd 1.3.9 and 1.4.3. Users should update to these versions as soon as they are released. It should be noted that containers started with an old version of containerd-shim should be stopped and restarted, as running containers will continue to be vulnerable even after an upgrade. If you are not providing the ability for untrusted users to start containers in the same network namespace as the shim (typically the "host" network namespace, for example with docker run --net=host or hostNetwork: true in a Kubernetes pod) and run with an effective UID of 0, you are not vulnerable to this issue. If you are running containers with a vulnerable configuration, you can deny access to all abstract sockets with AppArmor by adding a line similar to deny unix addr=@**, to your policy. It is best practice to run containers with a reduced set of privileges, with a non-zero UID, and with isolated namespaces. The containerd maintainers strongly advise against sharing namespaces with the host. Reducing the set of isolation mechanisms used for a container necessarily increases that container's privilege, regardless of what container runtime is used for running that container.

Is CVE-2020-15257 actively exploited?

Active exploitation of CVE-2020-15257 has not been confirmed. Its EPSS score was 3.1% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-15257?

CVE-2020-15257 has a CVSS v3 base score of 5.2 (MEDIUM severity), with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N.

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