CVE-2021-0254

Junos OS: Remote code execution vulnerability in overlayd service

CRITICAL

9.8

CVSS Score

Published: April 22, 2021 at 07:37 PM UTC

Updated: June 17, 2026 at 03:29 AM UTC

1 product affected across 1 vendorJunos

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Severity

CRITICAL9.8

Exploit prediction

EPSS 3%

Description

A buffer size validation vulnerability in the overlayd service of Juniper Networks Junos OS may allow an unauthenticated remote attacker to send specially crafted packets to the device, triggering a partial Denial of Service (DoS) condition, or leading to remote code execution (RCE). Continued receipt and processing of these packets will sustain the partial DoS. The overlayd daemon handles Overlay OAM packets, such as ping and traceroute, sent to the overlay. The service runs as root by default and listens for UDP connections on port 4789. This issue results from improper buffer size validation, which can lead to a buffer overflow. Unauthenticated attackers can send specially crafted packets to trigger this vulnerability, resulting in possible remote code execution. overlayd runs by default in MX Series, ACX Series, and QFX Series platforms. The SRX Series does not support VXLAN and is therefore not vulnerable to this issue. Other platforms are also vulnerable if a Virtual Extensible LAN (VXLAN) overlay network is configured. This issue affects Juniper Networks Junos OS: 15.1 versions prior to 15.1R7-S9; 17.3 versions prior to 17.3R3-S11; 17.4 versions prior to 17.4R2-S13, 17.4R3-S4; 18.1 versions prior to 18.1R3-S12; 18.2 versions prior to 18.2R2-S8, 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R1-S8, 18.4R2-S7, 18.4R3-S7; 19.1 versions prior to 19.1R2-S2, 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S2; 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-S1, 20.1R3; 20.2 versions prior to 20.2R2, 20.2R2-S1, 20.2R3; 20.3 versions prior to 20.3R1-S1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos · Juniper Networks

95%

15.1 ≤ v < 15.1R7-S917.3 ≤ v < 17.3R3-S1117.4 ≤ v < 17.4R2-S13, 17.4R3-S418.1 ≤ v < 18.1R3-S1218.2 ≤ v < 18.2R2-S8, 18.2R3-S718.3 ≤ v < 18.3R3-S418.4 ≤ v < 18.4R1-S8, 18.4R2-S7, 18.4R3-S719.1 ≤ v < 19.1R2-S2, 19.1R3-S419.2 ≤ v < 19.2R1-S6, 19.2R3-S219.3 ≤ v < 19.3R3-S119.4 ≤ v < 19.4R2-S4, 19.4R3-S120.1 ≤ v < 20.1R2-S1, 20.1R320.2 ≤ v < 20.2R2, 20.2R2-S1, 20.2R320.3 ≤ v < 20.3R1-S115.1 15.1 a1 15.1 f 15.1 f1 15.1 f2 15.1 f2-s1 15.1 f2-s2 15.1 f2-s3 15.1 f2-s4 15.1 f3 15.1 f4 15.1 f5 15.1 f5-s7 15.1 f6 15.1 f6-s1 15.1 f6-s10 15.1 f6-s12 15.1 f6-s2 15.1 f6-s3 15.1 f6-s4 15.1 f6-s5 15.1 f6-s6 15.1 f6-s7 15.1 f6-s8 15.1 f6-s9 15.1 f7 15.1 r 15.1 r1 15.1 r2 15.1 r3 15.1 r4 15.1 r4-s7 15.1 r4-s8 15.1 r4-s9 15.1 r5 15.1 r5-s1 15.1 r5-s3 15.1 r5-s5 15.1 r5-s6 15.1 r6 15.1 r6-s1 15.1 r6-s2 15.1 r6-s3 15.1 r6-s4 15.1 r6-s6 15.1 r7 15.1 r7-s1 15.1 r7-s2 15.1 r7-s3 15.1 r7-s4 15.1 r7-s5 15.1 r7-s6 15.1 r7-s7 15.1 r7-s8 17.3 17.3 r1 17.3 r1-s1 17.3 r1-s4 17.3 r2 17.3 r2-s1 17.3 r2-s2 17.3 r2-s3 17.3 r2-s4 17.3 r2-s5 17.3 r3 17.3 r3-s1 17.3 r3-s10 17.3 r3-s2 17.3 r3-s3 17.3 r3-s4 17.3 r3-s5 17.3 r3-s6 17.3 r3-s7 17.3 r3-s8 17.3 r3-s9 17.4 17.4 r1 17.4 r1-s1 17.4 r1-s2 17.4 r1-s3 17.4 r1-s4 17.4 r1-s5 17.4 r1-s6 17.4 r1-s7 17.4 r2 17.4 r2-s1 17.4 r2-s10 17.4 r2-s11 17.4 r2-s12 17.4 r2-s2 17.4 r2-s3 17.4 r2-s4 17.4 r2-s5 17.4 r2-s6 17.4 r2-s7 17.4 r2-s8 17.4 r2-s9 17.4 r3 17.4 r3-s1 17.4 r3-s2 17.4 r3-s3 18.1 18.1 r1 18.1 r2 18.1 r2-s1 18.1 r2-s2 18.1 r2-s4 18.1 r3 18.1 r3-s1 18.1 r3-s10 18.1 r3-s11 18.1 r3-s2 18.1 r3-s3 18.1 r3-s4 18.1 r3-s5 18.1 r3-s6 18.1 r3-s7 18.1 r3-s8 18.1 r3-s9 18.2 18.2 r1 18.2 r1-s2 18.2 r1-s3 18.2 r1-s4 18.2 r1-s5 18.2 r2 18.2 r2-s1 18.2 r2-s2 18.2 r2-s3 18.2 r2-s4 18.2 r2-s5 18.2 r2-s6 18.2 r2-s7 18.2 r3 18.2 r3-s1 18.2 r3-s2 18.2 r3-s3 18.2 r3-s4 18.2 r3-s5 18.2 r3-s6 18.3 18.3 r1 18.3 r1-s1 18.3 r1-s2 18.3 r1-s3 18.3 r1-s4 18.3 r1-s5 18.3 r1-s6 18.3 r2 18.3 r2-s1 18.3 r2-s2 18.3 r2-s3 18.3 r2-s4 18.3 r3 18.3 r3-s1 18.3 r3-s2 18.3 r3-s3 18.4 18.4 r1 18.4 r1-s1 18.4 r1-s2 18.4 r1-s3 18.4 r1-s4 18.4 r1-s5 18.4 r1-s6 18.4 r1-s7 18.4 r2 18.4 r2-s1 18.4 r2-s2 18.4 r2-s3 18.4 r2-s4 18.4 r2-s5 18.4 r2-s6 18.4 r3 18.4 r3-s1 18.4 r3-s2 18.4 r3-s3 18.4 r3-s4 18.4 r3-s5 18.4 r3-s6 19.1 19.1 r1 19.1 r1-s1 19.1 r1-s2 19.1 r1-s3 19.1 r1-s4 19.1 r1-s5 19.1 r2 19.1 r2-s1 19.1 r3 19.1 r3-s1 19.1 r3-s2 19.1 r3-s3 19.2 19.2 r1 19.2 r1-s1 19.2 r1-s2 19.2 r1-s3 19.2 r1-s4 19.2 r1-s5 19.2 r2 19.2 r2-s1 19.2 r3 19.2 r3-s1 19.3 19.3 r1 19.3 r1-s1 19.3 r2 19.3 r2-s1 19.3 r2-s2 19.3 r2-s3 19.3 r2-s4 19.3 r2-s5 19.3 r3 19.4 19.4 r1 19.4 r1-s1 19.4 r1-s2 19.4 r2 19.4 r2-s1 19.4 r2-s2 19.4 r2-s3 19.4 r3 20.1 20.1 r1 20.1 r1-s1 20.1 r1-s2 20.1 r1-s3 20.1 r1-s4 20.1 r2 20.2 20.2 r1 20.2 r1-s1 20.2 r1-s2 20.2 r1-s3 20.2 r2 20.3 20.3 r1

Affected range stops below 15.1R7-S9, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.3R3-S11, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.4R2-S13, 17.4R3-S4, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.1R3-S12, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.2R2-S8, 18.2R3-S7, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.3R3-S4, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.4R1-S8, 18.4R2-S7, 18.4R3-S7, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.1R2-S2, 19.1R3-S4, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.2R1-S6, 19.2R3-S2, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.3R3-S1, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.4R2-S4, 19.4R3-S1, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.1R2-S1, 20.1R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.2R2, 20.2R2-S1, 20.2R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.3R1-S1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://kb.juniper.net/JSA11147

References (1)

x_refsource_MISCVendor Advisory

Source: [email protected]

https://kb.juniper.net/JSA11147

CVSS

9.8CRITICALjuniper

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: HIGH
Availability: HIGH

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-131CWE-787

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