# What is CVE-2021-0217?

> CVE-2021-0217 is a high-severity flaw (CVSS 7.4) in Junos from Juniper, published on 15 January 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 0.7%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2021-0217

## 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:** 45 out of 100 (Medium); action: Plan remediation. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 7.4 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:** 0.7% (latest exploit-likelihood forecast)
- **Published:** 15 January 2021
- **Record last updated:** 5 August 2022
- **Main product:** Junos from Juniper
- **Affected products:** 21

## What is CVE-2021-0217? In plain terms

An attacker has to be on the same local network without logging in, and nobody has to click anything. If it works, the attacker can take it offline.

### The official description

A vulnerability in processing of certain DHCP packets from adjacent clients on EX Series and QFX Series switches running Juniper Networks Junos OS with DHCP local/relay server configured may lead to exhaustion of DMA memory causing a Denial of Service (DoS). Over time, exploitation of this vulnerability may cause traffic to stop being forwarded, or to crashing of the fxpc process. When Packet DMA heap utilization reaches 99%, the system will become unstable. Packet DMA heap utilization can be monitored through the following command: user@junos# request pfe execute target fpc0 timeout 30 command "show heap" ID Base Total(b) Free(b) Used(b) % Name -- ---------- ----------- ----------- ----------- --- ----------- 0 213301a8 536870488 387228840 149641648 27 Kernel 1 91800000 8388608 3735120 4653488 55 DMA 2 92000000 75497472 74452192 1045280 1 PKT DMA DESC 3 d330000 335544320 257091400 78452920 23 Bcm_sdk 4 96800000 184549376 2408 184546968 99 Packet DMA <--- 5 903fffe0 20971504 20971504 0 0 Blob An indication of the issue occurring may be observed through the following log messages: Dec 10 08:07:00.124 2020 hostname fpc0 brcm_pkt_buf_alloc:523 (buf alloc) failed allocating packet buffer Dec 10 08:07:00.126 2020 hostname fpc0 (buf alloc) failed allocating packet buffer Dec 10 08:07:00.128 2020 hostname fpc0 brcm_pkt_buf_alloc:523 (buf alloc) failed allocating packet buffer Dec 10 08:07:00.130 2020 hostnameC fpc0 (buf alloc) failed allocating packet buffer This issue affects Juniper Networks Junos OS on EX Series and QFX Series: 17.4R3 versions prior to 17.4R3-S3; 18.1R3 versions between 18.1R3-S6 and 18.1R3-S11; 18.2R3 versions prior to 18.2R3-S6; 18.3R3 versions prior to 18.3R3-S4; 18.4R2 versions prior to 18.4R2-S5; 18.4R3 versions prior to 18.4R3-S6; 19.1 versions between 19.1R2 and 19.1R3-S3; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R2-S5, 19.3R3; 19.4 versions prior to 19.4R2-S2, 19.4R3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R1-S2, 20.2R2. Junos OS versions prior to 17.4R3 are unaffected by this vulnerability.

### What kind of flaw is it?

- CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
- CWE-770: Allocation of Resources Without Limits or Throttling

### How an attack on it works

- Where an attacker can be: On the same local network
- How hard it is to pull off: Easy: no special conditions
- Login needed first: No login needed
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can take it offline

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

## Is CVE-2021-0217 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 0.7%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 0.7%, 0.7%, 0.7%, 0.7%, 0.7%, 0.7%, 0.7%.

### Timeline

- 15 January 2021: Published
- 5 August 2022: Record last updated

### How Precursor Intelligence ranks it

CVE-2021-0217 scores **45 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-2021-0217?

The published record lists 21 products.

- [Junos](https://www.precursorintelligence.com/product/juniper/junos) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Operating system): 17.4-r3, 17.4-r3-s1, 17.4-r3-s2, 18.1-r3-s7, 18.1-r3-s8, 18.1-r3-s9, 18.1-r3-s10, 18.2-r3, 18.2-r3-s1, 18.2-r3-s2, 18.2-r3-s3, 18.2-r3-s4, 18.2-r3-s5, 18.3-r3, 18.3-r3-s1, 18.3-r3-s2, 18.3-r3-s3, 18.4-r2, 18.4-r2-s1, 18.4-r2-s2, 18.4-r2-s3, 18.4-r2-s4, 19.1-r2-s1, 19.1-r3, 19.1-r3-s1, 19.1-r3-s2, 19.2, 19.2-r1, 19.2-r1-s1, 19.2-r1-s2, 19.2-r1-s3, 19.2-r1-s4, 19.2-r2, 19.2-r3, 19.3, 19.3-r1, 19.3-r1-s1, 19.3-r2, 19.3-r2-s1, 19.3-r2-s2 and 13 more
- [Ex2300](https://www.precursorintelligence.com/product/juniper/ex2300) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Ex2300-C](https://www.precursorintelligence.com/product/juniper/ex2300-c) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Ex2300m](https://www.precursorintelligence.com/product/juniper/ex2300m) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Ex3400](https://www.precursorintelligence.com/product/juniper/ex3400) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Ex4300](https://www.precursorintelligence.com/product/juniper/ex4300) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Ex4300m](https://www.precursorintelligence.com/product/juniper/ex4300m) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Ex4600](https://www.precursorintelligence.com/product/juniper/ex4600) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Ex4650](https://www.precursorintelligence.com/product/juniper/ex4650) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Ex9200](https://www.precursorintelligence.com/product/juniper/ex9200) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Ex9250](https://www.precursorintelligence.com/product/juniper/ex9250) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Qfx10002](https://www.precursorintelligence.com/product/juniper/qfx10002) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Qfx10008](https://www.precursorintelligence.com/product/juniper/qfx10008) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Qfx10016](https://www.precursorintelligence.com/product/juniper/qfx10016) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Qfx5100](https://www.precursorintelligence.com/product/juniper/qfx5100) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Qfx5110](https://www.precursorintelligence.com/product/juniper/qfx5110) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Qfx5120](https://www.precursorintelligence.com/product/juniper/qfx5120) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Qfx5130](https://www.precursorintelligence.com/product/juniper/qfx5130) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Qfx5200](https://www.precursorintelligence.com/product/juniper/qfx5200) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Qfx5210](https://www.precursorintelligence.com/product/juniper/qfx5210) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified
- [Qfx5220](https://www.precursorintelligence.com/product/juniper/qfx5220) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Hardware): version not specified

## How do I fix CVE-2021-0217?

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 advisory 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

- [kb.juniper.net](https://kb.juniper.net/JSA11107) (Exploit, Vendor advisory)

## Questions

### What is CVE-2021-0217?

CVE-2021-0217 is a high-severity flaw in Junos from Juniper, published on 15 January 2021. An attacker has to be on the same local network without logging in, and nobody has to click anything. If it works, the attacker can take it offline.

### How serious is CVE-2021-0217?

It scores 7.4 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2021-0217 is 45 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-2021-0217 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 0.7%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2021-0217 affect?

For Junos from Juniper: 17.4-r3, 17.4-r3-s1, 17.4-r3-s2, 18.1-r3-s7, 18.1-r3-s8, 18.1-r3-s9 and 47 more. The record lists 21 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2021-0217?

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-2021-0217 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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