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Fencer Vulns
medium 6.5

CVE-2021-0272 json

Junos OS: QFX10002-32Q, QFX10002-60C, QFX10002-72Q, QFX10008, QFX10016: In EVPN-VXLAN scenarios receipt of specific genuine packets by an adjacent attacker will cause a kernel memory leak in FPC.

published 2021-04-22 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-2891

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits
0
none known

Summary

A kernel memory leak in QFX10002-32Q, QFX10002-60C, QFX10002-72Q, QFX10008, QFX10016 devices Flexible PIC Concentrators (FPCs) on Juniper Networks Junos OS allows an attacker to send genuine packets destined to the device to cause a Denial of Service (DoS) to the device. On QFX10002-32Q, QFX10002-60C, QFX10002-72Q devices the device will crash and restart. On QFX10008, QFX10016 devices, depending on the number of FPCs involved in an attack, one more more FPCs may crash and traffic through the device may be degraded in other ways, until the attack traffic stops. A reboot is required to restore service and clear the kernel memory. Continued receipt and processing of these genuine packets will create a sustained Denial of Service (DoS) condition. On QFX10008, QFX10016 devices, an indicator of compromise may be the existence of DCPFE core files. You can also monitor PFE memory utilization for incremental growth: user@qfx-RE:0% cprod -A fpc0 -c "show heap 0" | grep -i ke 0 3788a1b0 3221225048 2417120656 804104392 24 Kernel user@qfx-RE:0% cprod -A fpc0 -c "show heap 0" | grep -i ke 0 3788a1b0 3221225048 2332332200 888892848 27 Kernel This issue affects: Juniper Networks Junos OS on QFX10002-32Q, QFX10002-60C, QFX10002-72Q, QFX10008, QFX10016: 16.1 versions 16.1R1 and above prior to 17.3 versions prior to 17.3R3-S9; 17.4 versions prior to 17.4R3-S2; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S5; 18.3 versions prior to 18.3R3-S3; 18.4 versions prior to 18.4R2-S5, 18.4R3-S4; 19.1 versions prior to 19.1R3-S2; 19.2 versions prior to 19.2R3; 19.3 versions prior to 19.3R3; 19.4 versions prior to 19.4R3; 20.1 versions prior to 20.1R2. This issue does not affect releases prior to Junos OS 16.1R1. This issue does not affect EX Series devices. This issue does not affect Junos OS Evolved.

Patch / fix

  • Juniper Networks Junos OS 17.3R3-S9, 17.4R3-S2, 18.1R3-S11, 18.2R3-S5, 18.3R3-S3, 18.4R2-S5, 18.4R3-S4, 19.1R3-S2, 19.2R3, 19.3R3, 19.4R3, 20.1R2

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 6.1 AV:A/AC:L/Au:N/C:N/I:N/A:C

Affected products

  • Juniper Networks Junos OS

Classification

Weakness
  • CWE-401 Missing Release of Memory after Effective Lifetime

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.