How severe is CVE-2021-43977?

CVE-2021-43977 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-43977 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-43977?

CVE-2021-43977 affects Smartertools Smartermail. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-43977?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-43977 published?

CVE-2021-43977 was published on 2021-11-17 and last updated on 2026-06-17.

CVE-2021-43977

CVE-2021-43977 is a medium-severity vulnerability in Smartertools Smartermail with a CVSS 3.x base score of 6.1. 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-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 1% (47th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Smartertools Smartermail
Published: 2021-11-17
Last modified: 2026-06-17

Description

SmarterTools SmarterMail 16.x through 100.x before 100.0.7803 allows XSS.

Frequently asked questions

What is CVE-2021-43977?: SmarterTools SmarterMail 16.x through 100.x before 100.0.7803 allows XSS.
How severe is CVE-2021-43977?: CVE-2021-43977 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-43977 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-43977?: CVE-2021-43977 affects Smartertools Smartermail. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-43977?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-43977 published?: CVE-2021-43977 was published on 2021-11-17 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:smartertools:smartermail:*:*:*:*:*:*:*:*

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