How severe is CVE-2021-45856?

CVE-2021-45856 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-45856 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-45856?

CVE-2021-45856 affects Accu-time Maximus Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-45856?

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-2021-45856 published?

CVE-2021-45856 was published on 2022-01-10 and last updated on 2026-06-17.

CVE-2021-45856

CVE-2021-45856 is a high-severity vulnerability in Accu-time Maximus Firmware with a CVSS 3.x base score of 7.5. 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-120.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (78th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Accu-time Maximus Firmware
Published: 2022-01-10
Last modified: 2026-06-17

Description

Accu-Time Systems MAXIMUS 1.0 telnet service suffers from a remote buffer overflow which causes the telnet service to crash

Frequently asked questions

What is CVE-2021-45856?: Accu-Time Systems MAXIMUS 1.0 telnet service suffers from a remote buffer overflow which causes the telnet service to crash
How severe is CVE-2021-45856?: CVE-2021-45856 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-45856 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-45856?: CVE-2021-45856 affects Accu-time Maximus Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-45856?: 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-2021-45856 published?: CVE-2021-45856 was published on 2022-01-10 and last updated on 2026-06-17.

References

https://packetstormsecurity.com/files/165392/Accu-Time-Systems-MAXIMUS-1.0-Buffer-Overflow-Denial-Of-Service.html

Affected products (1)

cpe:2.3:o:accu-time:maximus_firmware:1.0:*:*:*:*:*:*:*

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