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CVE Record

CVE-2019-19783: An issue was discovered in Cyrus IMAP before 2.5.15, 3.0.x before 3.0.13, and 3.1.x through 3.1.8.

An issue was discovered in Cyrus IMAP before 2.5.15, 3.0.x before 3.0.13, and 3.1.x through 3.1.8. If sieve script uploading is allowed (3.x) or certain non-default sieve options are enabled (2.x), a user with a mail account on the service can use a sieve script containing a fileinto directive to create any mailbox with administrator privileges, because of folder mishandling in autosieve_createfolder() in imap/lmtp_sieve.c.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2019-19783 affects Cyrus IMAP mail servers. In specific Sieve configurations, a normal mail user could cause mailbox creation to happen with administrator privileges. This is mainly a mail-system integrity and tenant-boundary concern, not evidence of unauthenticated internet compromise.

Executive priority

Treat this as a targeted mail-platform remediation item. It is not currently evidenced as actively exploited, but affected multi-user mail services should patch promptly because a regular account could cross administrative mailbox boundaries.

Technical view

The flaw is folder mishandling in autosieve_createfolder() in imap/lmtp_sieve.c. A Sieve script using a fileinto directive can create arbitrary mailboxes with administrator privileges when Sieve upload is allowed in 3.x or certain non-default Sieve options are enabled in 2.x.

Likely exposure

Exposure is limited to Cyrus IMAP before 2.5.15, 3.0.x before 3.0.13, and 3.1.x through 3.1.8 with the relevant Sieve capability or options enabled. Organizations running distro-packaged cyrus-imapd should check vendor advisory status.

Exploitation context

The provided sources do not show CISA KEV listing or active exploitation. Exploitation requires a valid mail account on the service plus vulnerable Sieve behavior. Risk rises in shared hosting, universities, ISPs, or multi-tenant mail systems.

Researcher notes

The affected condition is configuration-dependent. The source bundle identifies vulnerable version ranges and vendor advisories, but does not provide CVSS, CWE, exploit maturity, or detailed fixed handling for every branch. Avoid assuming unauthenticated access or remote code execution.

Mitigation direction

  • Upgrade Cyrus IMAP to a fixed vendor-supported release or distro security package.
  • Prioritize systems allowing user Sieve script uploads or Sieve folder auto-creation behavior.
  • If upgrade is delayed, review vendor guidance for reducing Sieve exposure.
  • Audit shared mail platforms where untrusted users can upload Sieve rules.

Validation and detection

  • Inventory Cyrus IMAP versions across mail servers and package-managed hosts.
  • Check whether Sieve script upload is enabled on Cyrus 3.x deployments.
  • Review Cyrus 2.x for non-default Sieve options tied to mailbox creation.
  • Confirm Debian, Ubuntu, Fedora, Gentoo, or upstream fixes are applied.
  • Test mail service behavior after updates using normal administrative validation only.
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

Conservative CVE-to-ATT&CK context

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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
9Source 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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