How severe is CVE-2021-34337?

CVE-2021-34337 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2021-34337 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34337?

CVE-2021-34337 affects Gnu Mailman. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-34337?

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

When was CVE-2021-34337 published?

CVE-2021-34337 was published on 2023-04-15 and last updated on 2026-06-17.

CVE-2021-34337

CVE-2021-34337 is a medium-severity vulnerability in Gnu Mailman with a CVSS 3.x base score of 6.3. 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-208.

Key facts

Severity: Medium (CVSS 3.x base score 6.3)
EPSS exploit prediction: 0% (22nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-208
Affected product: Gnu Mailman
Published: 2023-04-15
Last modified: 2026-06-17

Description

An issue was discovered in Mailman Core before 3.3.5. An attacker with access to the REST API could use timing attacks to determine the value of the configured REST API password and then make arbitrary REST API calls. The REST API is bound to localhost by default, limiting the ability for attackers to exploit this, but can optionally be made to listen on other interfaces.

Frequently asked questions

What is CVE-2021-34337?: An issue was discovered in Mailman Core before 3.3.5. An attacker with access to the REST API could use timing attacks to determine the value of the configured REST API password and then make arbitrary REST API calls. The REST API is bound to localhost by default, limiting the ability for attackers to exploit this, but can optionally be made to listen on other interfaces.
How severe is CVE-2021-34337?: CVE-2021-34337 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2021-34337 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34337?: CVE-2021-34337 affects Gnu Mailman. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-34337?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-34337 published?: CVE-2021-34337 was published on 2023-04-15 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:gnu:mailman:*:*:*:*:*:*:*:*

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