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AUSCERT External Security Bulletin Redistribution
Security Bulletin: Junos OS: Kernel crash (vmcore) or FPC
crash due to mbuf leak (CVE-2020-1653)
22 July 2020
AusCERT Security Bulletin Summary
Product: Junos OS
Publisher: Juniper Networks
Operating System: Juniper
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2020-1653
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2020-07 Security Bulletin: Junos OS: Kernel crash (vmcore) or FPC crash due to
mbuf leak (CVE-2020-1653)
Article ID : JSA11040
Last Updated: 21 Jul 2020
Version : 3.0
This issue affects Junos OS 17.4, 18.1, 18.2, 18.2X75, 18.3, 18.4, 19.1, 19.2,
On Juniper Networks Junos OS devices, a stream of TCP packets sent to the
Routing Engine (RE) may cause mbuf leak which can lead to Flexible PIC
Concentrator (FPC) crash or the system to crash and restart (vmcore).
This issue can be trigged by IPv4 or IPv6 and it is caused only by TCP packets.
This issue is not related to any specific configuration and it affects Junos OS
releases starting from 17.4R1.
However, this issue does not affect Junos OS releases prior to 18.2R1 when
Nonstop active routing (NSR) is configured [edit routing-options
The number of mbufs is platform dependent.
The following command provides the number of mbufs counter that are currently
in use and maximum number of mbufs that can be allocated on a platform:
user@host> show system buffers
2437/3143/5580 mbufs in use (current/cache/total)
Once the device runs out of mbufs, the FPC crashes or the vmcore occurs and the
device might become inaccessible requiring a manual restart.
This issue affects Juniper Networks Junos OS
17.4 versions prior to 17.4R2-S11, 17.4R3-S2;
18.1 versions prior to 18.1R3-S10;
18.2 versions prior to 18.2R2-S7, 18.2R3-S5;
18.2X75 versions prior to 18.2X75-D41, 18.2X75-D420.12, 18.2X75-D51,
18.3 versions prior to 18.3R2-S4, 18.3R3-S2;
18.4 versions prior to 18.4R1-S7, 18.4R2-S4, 18.4R3-S1;
19.1 versions prior to 19.1R1-S5, 19.1R2-S1, 19.1R3;
19.2 versions prior to 19.2R1-S5, 19.2R2;
19.3 versions prior to 19.3R2-S3, 19.3R3;
19.4 versions prior to 19.4R1-S2, 19.4R2.
Versions of Junos OS prior to 17.4R1 are unaffected by this vulnerability.
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
This issue was seen during production usage.
This issue has been assigned CVE-2020-1653 .
The following software releases have been updated to resolve this specific
issue: 17.4R2-S11, 17.4R3-S2, 18.1R3-S10, 18.2R2-S7, 18.2R3-S5, 18.2X75-D41,
18.2X75-D420.12, 18.2X75-D51, 18.2X75-D60, 18.2X75-D34, 18.3R2-S4, 18.3R3-S2,
18.4R1-S7, 18.4R2-S4, 18.4R3-S1, 19.1R1-S5, 19.1R2-S1, 19.1R3, 19.2R1-S5,
19.2R2, 19.3R2-S3, 19.3R3, 19.4R1-S2, 19.4R2, 20.1R1, and all subsequent
This issue is being tracked as 1468183 .
There are no viable workarounds for this issue, however having the DDoS feature
enabled and using the firewall filter to limit incoming packet towards the RE
only from trusted networks and host help to mitigate this issue.
The following command can be used to check if DDoS feature is enabled:
user@host> show ddos-protection statistics
DDOS protection global statistics:
Policing on routing engine: Yes <--- must be "Yes"
Policing on FPC: Yes
Software releases or updates are available for download at https://
2020-07-08: Initial publication
2020-07-21: Adding the PR reference
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common
Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."
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