What is CVE-2021-0263?A medium-severity flaw in Junos, explained.
CVE-2021-0263 is a medium-severity flaw (CVSS 5.9) in Junos from Juniper, published on 22 April 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 0.9%. If you run an affected version, plan in the vendor’s fix.
Published 22 April 2021. Record last updated 4 May 2021. We keep this page's data up to date.
What is CVE-2021-0263? In plain terms.
It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can take it offline.
A Data Processing vulnerability in the Multi-Service process (multi-svcs) on the FPC of Juniper Networks Junos OS on the PTX Series routers may lead to the process becoming unresponsive, ultimately affecting traffic forwarding, allowing an attacker to cause a Denial of Service (DoS) condition . The Multi-Service Process running on the FPC is responsible for handling sampling-related operations when a J-Flow configuration is activated. This can occur during periods of heavy route churn, causing the Multi-Service Process to stop processing updates, without consuming any further updates from kernel. This back pressure towards the kernel affects further dynamic updates from other processes in the system, including RPD, causing a KRT-STUCK condition and traffic forwarding issues. An administrator can monitor the following command to check if there is the KRT queue is stuck: user@device > show krt state ... Number of async queue entries: 65007 show chassis alarms 2 alarms currently active Alarm time Class Description 2020-10-11 04:33:45 PDT Minor Potential slow peers are: MSP(FPC1-PIC0) MSP(FPC3-PIC0) MSP(FPC4-PIC0) Logs: Oct 11 04:33:44.672 2020 test /kernel: rts_peer_cp_recv_timeout : Bit set for msp8 as it is stuck Oct 11 04:35:56.000 2020 test-lab fpc4 user.err gldfpc-multi-svcs.elf: Error in parsing composite nexthop Oct 11 04:35:56.000 2020 test-lab fpc4 user.err gldfpc-multi-svcs.elf: composite nexthop parsing error Oct 11 04:43:05 2020 test /kernel: rt_pfe_veto: Possible slowest client is msp38. States processed - 65865741. States to be processed - 0 Oct 11 04:55:55 2020 test /kernel: rt_pfe_veto: Memory usage of M_RTNEXTHOP type = (0) Max size possible for M_RTNEXTHOP type = (8311787520) Current delayed unref = (60000), Current unique delayed unref = (10896), Max delayed unref on this platform = (40000) Current delayed weight unref = (71426) Max delayed weight unref on this platform= (400000) curproc = rpd Oct 11 04:56:00 2020 test /kernel: rt_pfe_veto: Too many delayed route/nexthop unrefs. Op 2 err 55, rtsm_id 5:-1, msg type 2 This issue only affects PTX Series devices. No other products or platforms are affected by this vulnerability. This issue affects Juniper Networks Junos OS on PTX Series: 18.2 versions prior to 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R2-S8, 18.4R3-S7; 19.1 versions prior to 19.1R3-S4; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R2-S4, 19.4R3-S1; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R2; 20.3 versions prior to 20.3R1-S2, 20.3R2. This issue does not affect Juniper Networks Junos OS versions prior to 18.2R1.
What kind of flaw is it?
- UnknownUnknown
- UnknownUnknown
How an attack on it works
Read straight from its severity rating, translated out of the shorthand.
- Where an attacker can beAnywhere on the internet
- How hard it is to pull offHard: conditions must line up
- Login needed firstNo login needed
- Does someone have to clickNo, nobody has to do anything
- What an attacker getsCan take it offline
Severity vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Is CVE-2021-0263 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 0.9%. That can change at any time, which is why we keep watching.
Timeline
- Published
- Record last updated
CVE-2021-0263 scores 20. 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 isSmaller factor
- Threat activity around itSmaller factor
85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score.
When CVE-2021-0263 matches software you track, it lands in your list with its score and the reasons behind it.
See your own ranked list →Who is affected by CVE-2021-0263? 10 products.
The published record lists 10 products from 1 vendor. If you run one of these, check your version, then go to the fix below.
- Operating system
Junos
by Juniper
Affected versions18.218.2-r118.2-r1-s218.2-r1-s318.2-r1-s418.2-r1-s518.2-r218.2-r2-s118.2-r2-s218.2-r2-s318.2-r2-s418.2-r2-s518.2-r2-s618.2-r2-s7 - Hardware
Ptx1000
by Juniper
Affected versionsversion not specified - Hardware
Ptx10001-36mr
by Juniper
Affected versionsversion not specified - Hardware
Ptx10002
by Juniper
Affected versionsversion not specified - Hardware
Ptx10003
by Juniper
Affected versionsversion not specified - Hardware
Ptx10004
by Juniper
Affected versionsversion not specified - Hardware
Ptx10008
by Juniper
Affected versionsversion not specified - Hardware
Ptx10016
by Juniper
Affected versionsversion not specified - Hardware
Ptx3000
by Juniper
Affected versionsversion not specified
How do I fix CVE-2021-0263? Four steps.
- 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.
- 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.
- 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.
- 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.
Does CVE-2021-0263 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.
- Tell us what you runPick your software from a list, or let us work it out from your website.
- We match it to every flawOver 400,000 published flaws, checked against your list.
- Ranked by real-world riskA 0 to 100 score, led by evidence criminals are using it.
- Told as soon as we knowAn alert by email, in the app or by webhook to your own tools.
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1 new flaw affects software Acme tracks
A Data Processing vulnerability in the Multi-Service process (multi-svcs) on the FPC of Juniper Networks Junos OS on the PTX Series routers may lead to the p...
- Matched to
- Junos on Acme's software list
- What to do
- Plan in the vendor’s update
Sent to the alert recipients Acme chose. Also in the app and to Acme's webhook.
CVE-2021-0263 is a medium-severity flaw in Junos from Juniper, published on 22 April 2021. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can take it offline.
It scores 5.9 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2021-0263 is 20 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 0.9%. That can change at any time, which is why we keep watching.
For Junos from Juniper: 18.2, 18.2-r1, 18.2-r1-s2, 18.2-r1-s3, 18.2-r1-s4, 18.2-r1-s5 and 108 more. The record lists 10 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.