CVE-2021-40120
CVE-2021-40120 is a medium-severity vulnerability in Cisco Ios Xr with a CVSS 3.x base score of 6.5. 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-78.
Key facts
- Severity: Medium (CVSS 3.x base score 6.5)
- CVSS v2: 9.0
- EPSS exploit prediction: 2% (80th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-78
- Affected product: Cisco Ios Xr
- Published:
- Last modified:
Description
A vulnerability in the web-based management interface of certain Cisco Small Business RV Series Routers could allow an authenticated, remote attacker with administrative privileges to inject arbitrary commands into the underlying operating system and execute them using root-level privileges. This vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending malicious input to a specific field in the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying Linux operating system as a user with root-level privileges.
Frequently asked questions
- What is CVE-2021-40120?
- A vulnerability in the web-based management interface of certain Cisco Small Business RV Series Routers could allow an authenticated, remote attacker with administrative privileges to inject arbitrary commands into the underlying operating system and execute them using root-level privileges. This vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending malicious input to a specific field in the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying Linux operating system as a user with root-level privileges.
- How severe is CVE-2021-40120?
- CVE-2021-40120 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
- Is CVE-2021-40120 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (80th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-40120?
- CVE-2021-40120 primarily affects Cisco Ios Xr. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2021-40120?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- When was CVE-2021-40120 published?
- CVE-2021-40120 was published on 2021-11-04 and last updated on 2026-06-17.
References
Affected products (2)
- cpe:2.3:o:cisco:ios_xr:4.2.3.06:*:*:*:*:*:*:*
- cpe:2.3:a:cisco:application_extension_platform:1.5.1.13:*:*:*:*:*:*:*
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