CVE 2019 7524 Buffer overflow when reading extension header from Dovecot index files

Last modified: May 13, 2020

Background Information

We were made aware of a CVE in Dovecot Versions 2.0.14 - 2.3.5 that involves using Solr on Thursday, March 28th 2019.


  • 70 — 70.0.68

  • 76 — EOL

  • 78 — 78.0.20

  • CURRENT — 78.0.20

  • RELEASE — 78.0.20

  • STABLE — 78.0.20


According to the vendor, the risk involves a local root privilege escalation or executing arbitrary code in Dovecot process context.

The following lines in dovecot.conf are affected:

dovecot.conf: mail_plugins = quota quota_clone zlib fts fts_solr
dovecot.conf: mail_plugins = $mail_plugins zlib imap_zlib quota_clone virtual  fts fts_solr

How to determine if your server is up to date

The updated RPMs provided by cPanel will contain a changelog entry with the CVE number. You can check for this changelog entry with the following command:

rpm -q --changelog dovecot | grep CVE-2019-7524

This should give you output resembling the following:

- Patch for CVE-2019-7524


Dovecot Solr is an opt-in option that can be installed from the Mange Plugins interface of WHM.

If you have previously installed this plugin, we recommend uninstalling it from your cPanel & WHM until we have released patched versions.

In WHM, navigate to the WHM Plugins interface (WHM >> Home » cPanel » Manage Plugins) and uninstall Solr.

Official Upstream Security Report
Product: Dovecot
Vendor: OX Software GmbH
Internal reference: DOV-2964 (Bug ID)
Vulnerability type: CWE-120
Vulnerable version: 2.0.14 - 2.3.5
Vulnerable component: fts, pop3-uidl-plugin
Report confidence: Confirmed
Researcher credits: Found in internal testing
Solution status: Fixed by Vendor
Fixed version:,
Vendor notification: 2019-02-05
Solution date: 2019-03-21
Public disclosure: 2019-03-28
CVE reference: CVE-2019-7524
CVSS: 3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:P/RL:O/RC:C (8.8)

Vulnerability Details:
When reading FTS or POP3-UIDL header from dovecot index, the input
buffer size is not bound, and data is copied to target structure causing
stack overflow.

This can be used for local root privilege escalation or executing
arbitrary code in dovecot process context. This requires ability to
directly modify dovecot indexes.
Steps to reproduce:
Produce dovecot.index.log entry that creates an FTS header which has
more than 12 bytes of data.
Trigger dovecot indexer-worker or run doveadm index.
Dovecot will crash.

Since 2.3.0 dovecot has been compiled with stack smash protection, ASLR,
read-only GOT tables and other techniques that make exploiting this bug
much harder.

Operators should update to the latest Patch Release. The only workaround
is to disable FTS and pop3-uidl plugin.

Additional Documentation