How severe is CVE-2021-40112?

CVE-2021-40112 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-40112 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40112?

CVE-2021-40112 primarily affects Cisco Catalyst Pon Switch Cgp-ont-1p Firmware. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-40112?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-40112 published?

CVE-2021-40112 was published on 2021-11-04 and last updated on 2026-06-17.

CVE-2021-40112

CVE-2021-40112 is a critical-severity vulnerability in Cisco Catalyst Pon Switch Cgp-ont-1p Firmware with a CVSS 3.x base score of 10.0. 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-284.

Key facts

Severity: Critical (CVSS 3.x base score 10.0)
CVSS v2: 5.0
EPSS exploit prediction: 1% (70th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-284
Affected product: Cisco Catalyst Pon Switch Cgp-ont-1p Firmware
Published: 2021-11-04
Last modified: 2026-06-17

Description

Multiple vulnerabilities in the web-based management interface of the Cisco Catalyst Passive Optical Network (PON) Series Switches Optical Network Terminal (ONT) could allow an unauthenticated, remote attacker to perform the following actions: Log in with a default credential if the Telnet protocol is enabled Perform command injection Modify the configuration For more information about these vulnerabilities, see the Details section of this advisory.

Frequently asked questions

What is CVE-2021-40112?: Multiple vulnerabilities in the web-based management interface of the Cisco Catalyst Passive Optical Network (PON) Series Switches Optical Network Terminal (ONT) could allow an unauthenticated, remote attacker to perform the following actions: Log in with a default credential if the Telnet protocol is enabled Perform command injection Modify the configuration For more information about these vulnerabilities, see the Details section of this advisory.
How severe is CVE-2021-40112?: CVE-2021-40112 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-40112 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40112?: CVE-2021-40112 primarily affects Cisco Catalyst Pon Switch Cgp-ont-1p Firmware. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-40112?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-40112 published?: CVE-2021-40112 was published on 2021-11-04 and last updated on 2026-06-17.

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-catpon-multivulns-CE3DSYGr

Affected products (5)

cpe:2.3:o:cisco:catalyst_pon_switch_cgp-ont-1p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:catalyst_pon_switch_cgp-ont-4p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:catalyst_pon_switch_cgp-ont-4pvc_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:catalyst_pon_switch_cgp-ont-4tvcw_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:catalyst_pon_switch_cgp-ont-4pv_firmware:*:*:*:*:*:*:*:*

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CVE-2021-40113 — Critical (CVSS 10.0): Multiple vulnerabilities in the web-based management interface of the Cisco Catalyst Passive Optical Network (PON)…
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