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CVE Record

CVE-2020-28200: The Sieve engine in Dovecot before 2.3.15 allows Uncontrolled Resource Consumption, as demonstrated by a si...

The Sieve engine in Dovecot before 2.3.15 allows Uncontrolled Resource Consumption, as demonstrated by a situation with a complex regular expression for the regex extension.

MediumCVSS 4.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This issue lets an authenticated mail user make Dovecot's Sieve mail-filtering engine consume excessive resources through a complex regular expression. The documented impact is availability only, not data theft or message tampering. Risk is moderate where users can create or run Sieve scripts on Dovecot versions before 2.3.15.

Executive priority

Prioritize normal patching for internet-facing or shared Dovecot mail services. Escalate if many untrusted mailbox users can create Sieve rules, because the realistic business impact is mail service degradation rather than compromise of confidentiality.

Technical view

CVE-2020-28200 is uncontrolled resource consumption in the Dovecot Sieve engine before 2.3.15, demonstrated with complex regular expressions in the regex extension. CVSS 3.1 is 4.3: network reachable, low privileges required, no user interaction, and low availability impact only.

Likely exposure

Most likely exposed systems are Dovecot mail servers before 2.3.15 where authenticated users can use Sieve filtering, especially regex-based filtering. The provided CVE data does not enumerate specific distributions beyond Fedora advisories.

Exploitation context

The source bundle does not show CISA KEV listing or active exploitation. Exploitation requires low privileges, so this is more relevant for shared mail platforms or environments with many mailbox users than unauthenticated internet exposure.

Researcher notes

The provided affected-product metadata is incomplete, but the CVE description names Dovecot before 2.3.15. The evidence supports availability impact via Sieve regex processing with low privileges. No source in the bundle supports active exploitation or confidentiality/integrity impact.

Mitigation direction

  • Upgrade Dovecot to 2.3.15 or later where applicable.
  • Apply distribution vendor updates, including relevant Fedora advisories if using Fedora packages.
  • Review Dovecot security guidance for version-specific remediation details.
  • Limit Sieve script capability to trusted users where operationally feasible.

Validation and detection

  • Inventory Dovecot servers and record installed versions.
  • Confirm whether any server is older than Dovecot 2.3.15.
  • Identify whether users can create or run Sieve scripts.
  • Check package advisory status on affected Linux distributions.
  • Monitor mail service resource usage for abnormal Sieve processing impact.
Prepared
Confidence
high
Sources
6

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

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2020-28200 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
4.3 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AC:L/AV:N/A:L/C:N/I:N/PR:L/S:U/UI:N

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.

1CVSS vectors
0Timeline events
0ADP providers
5Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
4.3CVSS 3.1MediumCVSS:3.1/AC:L/AV:N/A:L/C:N/I:N/PR:L/S:U/UI:N2.81.4Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

4.3Medium
CVSS 3.1 vector shape for CVE-2020-28200Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AC:L/AV:N/A:L/C:N/I:N/PR:L/S:U/UI:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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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