CVE-2021-0278

CVE-2021-0278 is a high-severity vulnerability in Juniper Junos with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Description

An Improper Input Validation vulnerability in J-Web of Juniper Networks Junos OS allows a locally authenticated attacker to escalate their privileges to root over the target device. junos:18.3R3-S5 junos:18.4R3-S9 junos:19.1R3-S6 junos:19.3R2-S6 junos:19.3R3-S3 junos:19.4R1-S4 junos:19.4R3-S4 junos:20.1R2-S2 junos:20.1R3 junos:20.2R3-S1 junos:20.3X75-D20 junos:20.3X75-D30 junos:20.4R2-S1 junos:20.4R3 junos:21.1R1-S1 junos:21.1R2 junos:21.2R1 junos:21.3R1 This issue affects: Juniper Networks Junos OS 19.3 versions 19.3R1 and above prior to 19.3R2-S6, 19.3R3-S3; 19.4 versions prior to 19.4R3-S5; 20.1 versions prior to 20.1R2-S2, 20.1R3-S1; 20.2 versions prior to 20.2R3-S2; 20.3 versions prior to 20.3R3; 20.4 versions prior to 20.4R2-S1, 20.4R3; 21.1 versions prior to 21.1R1-S1, 21.1R2. This issue does not affect Juniper Networks Junos OS versions prior to 19.3R1.

Frequently asked questions

What is CVE-2021-0278?
An Improper Input Validation vulnerability in J-Web of Juniper Networks Junos OS allows a locally authenticated attacker to escalate their privileges to root over the target device. junos:18.3R3-S5 junos:18.4R3-S9 junos:19.1R3-S6 junos:19.3R2-S6 junos:19.3R3-S3 junos:19.4R1-S4 junos:19.4R3-S4 junos:20.1R2-S2 junos:20.1R3 junos:20.2R3-S1 junos:20.3X75-D20 junos:20.3X75-D30 junos:20.4R2-S1 junos:20.4R3 junos:21.1R1-S1 junos:21.1R2 junos:21.2R1 junos:21.3R1 This issue affects: Juniper Networks Junos OS 19.3 versions 19.3R1 and above prior to 19.3R2-S6, 19.3R3-S3; 19.4 versions prior to 19.4R3-S5; 20.1 versions prior to 20.1R2-S2, 20.1R3-S1; 20.2 versions prior to 20.2R3-S2; 20.3 versions prior to 20.3R3; 20.4 versions prior to 20.4R2-S1, 20.4R3; 21.1 versions prior to 21.1R1-S1, 21.1R2. This issue does not affect Juniper Networks Junos OS versions prior to 19.3R1.
How severe is CVE-2021-0278?
CVE-2021-0278 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-0278 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-0278?
CVE-2021-0278 primarily affects Juniper Junos. In total, 50 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-0278?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-0278 published?
CVE-2021-0278 was published on 2021-07-15 and last updated on 2026-06-17.

References

Affected products (50)

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