CVE 2019 7524 Buffer overflow when reading extension header from Dovecot index files
Last modified: December 2, 2022
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.
Releases
- 70 — 70.0.68
- 76 — EOL
- 78 — 78.0.20
- CURRENT — 78.0.20
- RELEASE — 78.0.20
- STABLE — 78.0.20
Impact
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:
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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
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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
Mitigation
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.
To uninstall, navigate to WHM’s Manage Plugins interface (WHM » Home » cPanel » Manage Plugins) and uninstall Solr.
Official Upstream Security Report
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https://www.dovecot.org/pipermail/dovecot-news/2019-March/000403.html
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: 2.3.5.1, 2.2.36.3
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.
Risk:
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.
Mitigations:
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.
Solution:
Operators should update to the latest Patch Release. The only workaround
is to disable FTS and pop3-uidl plugin.
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