CVE-2021-0223

CVE-2021-0223 is a high-severity vulnerability in Juniper Junos with a CVSS 3.x base score of 7.8. 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-269.

Key facts

Description

A local privilege escalation vulnerability in telnetd.real of Juniper Networks Junos OS may allow a locally authenticated shell user to escalate privileges and execute arbitrary commands as root. telnetd.real is shipped with setuid permissions enabled and is owned by the root user, allowing local users to run telnetd.real with root privileges. This issue affects Juniper Networks Junos OS: all versions prior to 15.1R7-S9; 17.3 versions prior to 17.3R3-S11; 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S6; 18.3 versions prior to 18.3R2-S4, 18.3R3-S4; 18.4 versions prior to 18.4R2-S7, 18.4R3-S6; 19.1 versions prior to 19.1R2-S2, 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S1; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R2-S2, 19.4R3; 20.1 versions prior to 20.1R1-S4, 20.1R2; 20.2 versions prior to 20.2R2.

Frequently asked questions

What is CVE-2021-0223?
A local privilege escalation vulnerability in telnetd.real of Juniper Networks Junos OS may allow a locally authenticated shell user to escalate privileges and execute arbitrary commands as root. telnetd.real is shipped with setuid permissions enabled and is owned by the root user, allowing local users to run telnetd.real with root privileges. This issue affects Juniper Networks Junos OS: all versions prior to 15.1R7-S9; 17.3 versions prior to 17.3R3-S11; 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S6; 18.3 versions prior to 18.3R2-S4, 18.3R3-S4; 18.4 versions prior to 18.4R2-S7, 18.4R3-S6; 19.1 versions prior to 19.1R2-S2, 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S1; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R2-S2, 19.4R3; 20.1 versions prior to 20.1R1-S4, 20.1R2; 20.2 versions prior to 20.2R2.
How severe is CVE-2021-0223?
CVE-2021-0223 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-0223 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-0223?
CVE-2021-0223 primarily affects Juniper Junos. In total, 197 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-0223?
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-2021-0223 published?
CVE-2021-0223 was published on 2021-01-15 and last updated on 2026-06-17.

References

Affected products (197)

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