CVE-2021-1539: Cisco ASR 5000 Series Software Authorization Bypass Vulnerabilities

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-06-04 · updated 2026-06-17
Weakness: CWE-863

Description

Multiple vulnerabilities in the authorization process of Cisco ASR 5000 Series Software (StarOS) could allow an authenticated, remote attacker to bypass authorization and execute a subset of CLI commands on an affected device. For more information about these vulnerabilities, see the Details section of this advisory.

Affected products

Cisco StarOS: before 21.16.9; from 21.17.0 before 21.17.10; from 21.18.0 before 21.18.16; from 21.19.0 before 21.19.11; from 21.19.n before 21.19.n7; from 21.20.0 before 21.20.8 — fixed in 21.16.9, 21.17.10, 21.18.16, 21.19.11, 21.19.n7, 21.20.8
Cisco Virtualized Packet Core-Distributed Instance: all versions

How to fix

Upgrade to a fixed version: Cisco StarOS 21.16.9, 21.17.10, 21.18.16, 21.19.11. Check the vendor advisory for mitigations.

References

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