CVE detail

CVE-2021-0251 — CVE-2021-0251

Published 2021-04-22 · Modified 2026-06-17 · Vendor juniper · Product junos · Source nvd
HIGH
severity
CVSS-derived band
8.6
CVSS v3
0–10 scale
0.0106
EPSS probability
exploitation probability, 30d
62.0%
EPSS percentile
percentile vs all CVEs
NOT LISTED
CISA KEV
known exploited catalog

Description

A NULL Pointer Dereference vulnerability in the Captive Portal Content Delivery (CPCD) services daemon (cpcd) of Juniper Networks Junos OS on MX Series with MS-PIC, MS-SPC3, MS-MIC or MS-MPC allows an attacker to send malformed HTTP packets to the device thereby causing a Denial of Service (DoS), crashing the Multiservices PIC Management Daemon (mspmand) process thereby denying users the ability to login, while concurrently impacting other mspmand services and traffic through the device. Continued receipt and processing of these malformed packets will create a sustained Denial of Service (DoS) condition. While the Services PIC is restarting, all PIC services will be bypassed until the Services PIC completes its boot process. An attacker sending these malformed HTTP packets to the device wh

Remediation

vendor remediation guidance

The following software releases have been updated to resolve this specific issue: 17.4R2-S9, 17.4R3-S2, 18.1R3-S9, 18.2R3-S3, 18.3R3-S1, 18.4R3, 19.1R2-S2, 19.1R3, 19.2R2, 19.3R3, 19.4R1, and all subsequent releases.

workarounds

There are no viable workarounds for this issue other than disabling the captive portal services.

ProductVulnerable rangeFixed versionAdvisory
Juniper Networks Junos OS>=17.3R1<17.3*17.3*advisory ↗
Juniper Networks Junos OS>=17.4<17.4R2-S9, 17.4R3-S217.4R2-S9, 17.4R3-S2advisory ↗
Juniper Networks Junos OS>=18.1<18.1R3-S918.1R3-S9advisory ↗
Juniper Networks Junos OS>=18.2<18.2R3-S318.2R3-S3advisory ↗
Juniper Networks Junos OS>=18.3<18.3R3-S118.3R3-S1advisory ↗
Juniper Networks Junos OS>=18.4<18.4R318.4R3advisory ↗
Juniper Networks Junos OS>=19.1<19.1R2-S2, 19.1R319.1R2-S2, 19.1R3advisory ↗
Juniper Networks Junos OS>=19.2<19.2R219.2R2advisory ↗
Juniper Networks Junos OS>=19.3<19.3R319.3R3advisory ↗

References

cvedb.io · NVD · CISA KEV · FIRST EPSS · vendor advisories (CVE Program List v5). Informational only, no warranty — verify every remediation against the vendor advisory before acting on it. This product uses data from the NVD API but is not endorsed or certified by the NVD, CISA, FIRST.org or any vendor named. CVE® is a registered trademark of The MITRE Corporation.