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What is CVE-2020-15257?A medium-severity flaw in Containerd, explained.

Medium severity3 affected products
The short answer

CVE-2020-15257 is a medium-severity flaw (CVSS 5.2) in Containerd from Linuxfoundation, published on 1 December 2020. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 3.2%. If you run an affected version, plan in the vendor’s fix.

Check if it affects you →How to fix it

Published 1 December 2020. Record last updated 7 November 2023. We keep this page's data up to date.

What it does

What is CVE-2020-15257? In plain terms.

An attacker has to be already on the device with an ordinary user account, and nobody has to click anything. If it works, the attacker can read some data and change some data.

The official 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.

What kind of flaw is it?

  • CWE-669Incorrect Resource Transfer Between Spheres
CVSS 3.1 scoreMedium · 5.2

How an attack on it works

Read straight from its severity rating, translated out of the shorthand.

  • Where an attacker can beAlready on the device
  • How hard it is to pull offEasy: no special conditions
  • Login needed firstAn ordinary user account
  • Does someone have to clickNo, nobody has to do anything
  • What an attacker getsCan read some data and change some data

Severity vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

Exploitation

Is CVE-2020-15257 being exploited? Not that we know of.

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 3.2%. That can change at any time, which is why we keep watching.

Known to be exploitedNoNot on the list of exploited flaws today
Chance of use in the next 30 days3.2%Its EPSS score, from the latest forecast

Timeline

  1. Published
  2. Record last updated
How Precursor Intelligence ranks it
34out of 100Low

CVE-2020-15257 scores 34. Action: Monitor.

We keep the score of every published flaw up to date as the evidence changes. Four things go into the score, and evidence that criminals are actually using it counts most. In order:

  • Evidence it is being exploitedBiggest factor
  • How severe it isStrong factor
  • How widely exposed it isKey context
  • Real threat activity around itKey context

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score.

When CVE-2020-15257 matches software you track, it lands in your list with its score and the reasons behind it.

See your own ranked list →
Affected products

Who is affected by CVE-2020-15257? 3 products.

The published record lists 3 products from 3 vendors. Versions are shown as published: "before 1.3.9" means every version up to, but not including, 1.3.9. If you run one of these, check your version, then go to the fix below.

Remediation

How do I fix CVE-2020-15257? Four steps.

  1. Check whether you run itCompare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
  2. Apply the vendor’s fixInstall the update named in the vendor’s advisory. We’ve put the advisories and patch notes first in the list.
  3. If you can’t patch todayFollow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
  4. Keep an eye on itTrack the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood.

References

6 links
Precursor Intelligence

Does CVE-2020-15257 affect you? We'll keep checking.

Looking flaws up one at a time doesn't scale. Tell us what you run once, and we tell you which flaws matter to you, in what order, and keep watching for new ones.

  1. Tell us what you runPick your software from a list, or let us work it out from your website.
  2. We match it to every flawOver 400,000 published flaws, checked against your list.
  3. Ranked by real-world riskA 0 to 100 score, led by evidence criminals are using it.
  4. Told as soon as we knowAn alert by email, in the app or by webhook to your own tools.
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CVE-2020-15257 is a medium-severity flaw in Containerd from Linuxfoundation, published on 1 December 2020. An attacker has to be already on the device with an ordinary user account, and nobody has to click anything. If it works, the attacker can read some data and change some data.

It scores 5.2 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2020-15257 is 34 out of 100, which is Low. Its action is "Monitor". No sign of exploitation and a low forecast. Patch it in your normal update cycle.

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 3.2%. That can change at any time, which is why we keep watching.

For Containerd from Linuxfoundation: before 1.3.9, 1.4.0 to before 1.4.3. The record lists 3 products in all, each with its versions, under "Who is affected" on this page.

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet.

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