How severe is CVE-2021-40347?

CVE-2021-40347 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-40347 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40347?

CVE-2021-40347 affects Postorius Project Postorius. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-40347?

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

When was CVE-2021-40347 published?

CVE-2021-40347 was published on 2021-09-10 and last updated on 2026-06-17.

CVE-2021-40347

CVE-2021-40347 is a medium-severity vulnerability in Postorius Project Postorius with a CVSS 3.x base score of 5.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
CVSS v2: 5.5
EPSS exploit prediction: 1% (64th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Postorius Project Postorius
Published: 2021-09-10
Last modified: 2026-06-17

Description

An issue was discovered in views/list.py in GNU Mailman Postorius before 1.3.5. An attacker (logged into any account) can send a crafted POST request to unsubscribe any user from a mailing list, also revealing whether that address was subscribed in the first place.

Frequently asked questions

What is CVE-2021-40347?: An issue was discovered in views/list.py in GNU Mailman Postorius before 1.3.5. An attacker (logged into any account) can send a crafted POST request to unsubscribe any user from a mailing list, also revealing whether that address was subscribed in the first place.
How severe is CVE-2021-40347?: CVE-2021-40347 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-40347 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40347?: CVE-2021-40347 affects Postorius Project Postorius. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-40347?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-40347 published?: CVE-2021-40347 was published on 2021-09-10 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:postorius_project:postorius:*:*:*:*:*:*:*:*