# What is CVE-2020-27815?

> CVE-2020-27815 is a high-severity flaw (CVSS 7.8) in Linux kernel, published on 26 May 2021. 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 0.8%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2020-27815

## At a glance

- **Verdict:** Plan it in. No sign of exploitation and a low forecast. Patch it in your normal update cycle.
- **Precursor Intelligence risk score:** 50 out of 100 (Medium); action: Plan remediation. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 7.8 out of 10)
- **Known to be exploited:** No, not on the list of flaws known to be exploited today
- **Chance of use in the next 30 days:** 0.8% (latest exploit-likelihood forecast)
- **Published:** 26 May 2021
- **Record last updated:** 28 July 2023
- **Main product:** Linux kernel
- **Affected products:** 22

## What is CVE-2020-27815? 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 data, change data and take it offline.

### The official description

A flaw was found in the JFS filesystem code in the Linux Kernel which allows a local attacker with the ability to set extended attributes to panic the system, causing memory corruption or escalating privileges. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

### What kind of flaw is it?

- CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
- CWE-787: Out-of-bounds Write

### How an attack on it works

- Where an attacker can be: Already on the device
- How hard it is to pull off: Easy: no special conditions
- Login needed first: An ordinary user account
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can read data, change data and take it offline

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

## Is CVE-2020-27815 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 0.8%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 0.8%, 0.8%, 0.8%, 0.8%, 0.8%, 0.8%, 0.8%.

### Timeline

- 26 May 2021: Published
- 28 July 2023: Record last updated

### How Precursor Intelligence ranks it

CVE-2020-27815 scores **50 out of 100 (Medium)**, with the action "Plan remediation".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2020-27815?

The published record lists 22 products. Versions are as published: "4.5 to before 4.9.249" means from 4.5 up to, but not including, 4.9.249.

- [Linux kernel](https://www.precursorintelligence.com/product/linux/linux_kernel) by [Linux](https://www.precursorintelligence.com/vendors/linux) (Operating system): after 4.4.249, 4.5 to before 4.9.249, 4.10 to before 4.14.213, 4.15 to before 4.19.164, 4.20 to before 5.4.86, 5.5 to before 5.10.4
- [Debian Linux](https://www.precursorintelligence.com/product/debian/debian_linux) by [Debian](https://www.precursorintelligence.com/vendors/debian) (Operating system): 9.0, 10.0
- [Aff A250](https://www.precursorintelligence.com/product/netapp/aff_a250) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified
- [Aff A250 Firmware](https://www.precursorintelligence.com/product/netapp/aff_a250_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified
- [Fas500f](https://www.precursorintelligence.com/product/netapp/fas500f) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified
- [Fas500f Firmware](https://www.precursorintelligence.com/product/netapp/fas500f_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified
- [H300e](https://www.precursorintelligence.com/product/netapp/h300e) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified
- [H300e Firmware](https://www.precursorintelligence.com/product/netapp/h300e_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified
- [H300s](https://www.precursorintelligence.com/product/netapp/h300s) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified
- [H300s Firmware](https://www.precursorintelligence.com/product/netapp/h300s_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified
- [H410c](https://www.precursorintelligence.com/product/netapp/h410c) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified
- [H410c Firmware](https://www.precursorintelligence.com/product/netapp/h410c_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified
- [H410s](https://www.precursorintelligence.com/product/netapp/h410s) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified
- [H410s Firmware](https://www.precursorintelligence.com/product/netapp/h410s_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified
- [H500e](https://www.precursorintelligence.com/product/netapp/h500e) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified
- [H500e Firmware](https://www.precursorintelligence.com/product/netapp/h500e_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified
- [H500s](https://www.precursorintelligence.com/product/netapp/h500s) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified
- [H500s Firmware](https://www.precursorintelligence.com/product/netapp/h500s_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified
- [H700e](https://www.precursorintelligence.com/product/netapp/h700e) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified
- [H700e Firmware](https://www.precursorintelligence.com/product/netapp/h700e_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified
- [H700s](https://www.precursorintelligence.com/product/netapp/h700s) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Hardware): version not specified
- [H700s Firmware](https://www.precursorintelligence.com/product/netapp/h700s_firmware) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Operating system): version not specified

## How do I fix CVE-2020-27815?

1. **Check whether you run it.** Compare 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 fix.** Install 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 today.** Follow 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 it.** Track 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

- [openwall.com](http://www.openwall.com/lists/oss-security/2020/12/28/1) (Exploit, Mailing list, Patch, Third-party advisory)
- [git.kernel.org](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c61b3e4839007668360ed8b87d7da96d2e59fc6c) (Patch, Vendor advisory)
- [openwall.com](http://www.openwall.com/lists/oss-security/2020/11/30/5) (Exploit, Mailing list, Third-party advisory)
- [bugzilla.redhat.com](https://bugzilla.redhat.com/show_bug.cgi?id=1897668%2C) (Issue tracking)
- [lists.debian.org](https://lists.debian.org/debian-lts-announce/2021/02/msg00018.html) (Mailing list, Third-party advisory)
- [lists.debian.org](https://lists.debian.org/debian-lts-announce/2021/03/msg00010.html) (Mailing list, Third-party advisory)
- [security.netapp.com](https://security.netapp.com/advisory/ntap-20210702-0004/) (Third-party advisory)
- [debian.org](https://www.debian.org/security/2021/dsa-4843) (Third-party advisory)
- [openwall.com](https://www.openwall.com/lists/oss-security/2020/11/30/5%2C) (Mailing list)
- [openwall.com](https://www.openwall.com/lists/oss-security/2020/12/28/1%2C) (Mailing list)

## Questions

### What is CVE-2020-27815?

CVE-2020-27815 is a high-severity flaw in Linux kernel, published on 26 May 2021. 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 data, change data and take it offline.

### How serious is CVE-2020-27815?

It scores 7.8 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2020-27815 is 50 out of 100, which is Medium. Its action is "Plan remediation". No sign of exploitation and a low forecast. Patch it in your normal update cycle.

### Is CVE-2020-27815 being exploited?

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 0.8%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2020-27815 affect?

For Linux kernel: after 4.4.249, 4.5 to before 4.9.249, 4.10 to before 4.14.213, 4.15 to before 4.19.164, 4.20 to before 5.4.86, 5.5 to before 5.10.4. The record lists 22 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2020-27815?

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.

## Does CVE-2020-27815 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

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