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CVE Record

CVE-2021-40347: An issue was discovered in views/list.py in GNU Mailman Postorius before 1.3.5.

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

GNU Mailman Postorius before 1.3.5 let any logged-in account unsubscribe other users from mailing lists. The issue could disrupt communications and expose whether a specific email address was subscribed. It is not described as remote code execution or full account compromise in the provided sources.

Executive priority

Treat this as a moderate operational and privacy issue. Prioritize patching public or broadly accessible Postorius deployments because the impact can silently disrupt mailing list communications and reveal membership status.

Technical view

The reported flaw is in Postorius views/list.py. An authenticated attacker could submit a crafted POST request that affected another user's subscription state and disclosed subscription presence. The CVE names GNU Mailman Postorius before 1.3.5; Debian issued DSA-4970 and an upstream commit is cited.

Likely exposure

Exposure is likely for organizations running GNU Mailman Postorius before 1.3.5, especially where untrusted or broad user populations can log in. The source bundle does not provide CPEs, CVSS, or a full distribution/version matrix.

Exploitation context

The CVE describes exploitation by a logged-in user against mailing list subscription management. KEV is false, and the provided sources do not state active exploitation in the wild.

Researcher notes

Evidence is concise but consistent: the CVE description, upstream issue, commit reference, tag reference, and Debian advisory point to Postorius before 1.3.5. Missing details include CVSS, CWE, precise fixed Debian versions in this prompt, and confirmed exploitation telemetry.

Mitigation direction

  • Upgrade GNU Mailman Postorius to 1.3.5 or later where applicable.
  • Apply Debian DSA-4970 packages if using affected Debian distributions.
  • Check GNU Mailman and distribution advisories for backported fixed package versions.
  • Limit Postorius access to trusted users until updates are completed.
  • Review recent list membership changes for unexpected unsubscribes.

Validation and detection

  • Inventory all deployed Postorius instances and record exact versions.
  • Confirm whether instances are earlier than Postorius 1.3.5.
  • Check package changelogs or advisory metadata for the cited fix.
  • Review access logs for suspicious authenticated subscription-management activity.
  • Verify mailing list membership against expected subscriber records.
Prepared
Confidence
high
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
7Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

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