CVE-2021-0254: juniper networks junos os Incorrect Calculation of Buffer Size
Vulnerability summary
CVE-2021-0254 is a critical (CVSS 9.8) Incorrect Calculation of Buffer Size vulnerability in juniper networks junos os. EPSS estimates a 2.57% chance of exploitation in the next 30 days, higher than 84.9% of scored vulnerabilities.
Timeline
- 22-04-2021PublishedVulnerability first disclosed.
- 16-09-2024Last modifiedVulnerability information updated.
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.
CVSS metrics
3 scores · 2 sources · 2 versions- NVDNIST9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
2.57%
Chance of exploitation in the next 30 days
Percentile
85%
Versus all other CVEs
30-day change
0.00 pp
From 2.57% on 20-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Juniper1 product
- junos15.1 | 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: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:r1 | 20.1:r1-s1 | 20.1:r1-s2 | 20.1:r1-s3 | 20.1:r1-s4 | 20.1:r2 | 20.2:r1 | 20.2:r1-s1 | 20.2:r1-s2 | 20.2:r1-s3 | 20.2:r2 | 20.3:r1
Juniper networks1 product
- junos os≥ 15.1, < 15.1R7-S9 | ≥ 17.3, < 17.3R3-S11 | ≥ 17.4, < 17.4R2-S13, 17.4R3-S4 | ≥ 18.1, < 18.1R3-S12 | ≥ 18.2, < 18.2R2-S8, 18.2R3-S7 | ≥ 18.3, < 18.3R3-S4 | ≥ 18.4, < 18.4R1-S8, 18.4R2-S7, 18.4R3-S7 | ≥ 19.1, < 19.1R2-S2, 19.1R3-S4 | ≥ 19.2, < 19.2R1-S6, 19.2R3-S2 | ≥ 19.3, < 19.3R3-S1 | ≥ 19.4, < 19.4R2-S4, 19.4R3-S1 | ≥ 20.1, < 20.1R2-S1, 20.1R3 | ≥ 20.2, < 20.2R2, 20.2R2-S1, 20.2R3 | ≥ 20.3, < 20.3R1-S1
2 vendors · 2 products